Root cause insight into the common BMW blower motor resistor failures

[Bimmer Owner]

Does anyone have insight into what is the root cause (and repair) of the
FSU failure that plagues almost every 1997 to 2003 BMW?
http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994

Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
or by FSU (Final Stage Unit), is known to fry itself in almost every single
E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
http://www.bimmerfest.com/forums/showthread.php?t=143393

The problem with replacing this ~$100 part is that the new replacement FSU
fries itself just as often as the old one did, so you end up repeatedly
replacing your fried FSU every few years or so.
http://www.bimmerfest.com/forums/showthread.php?t=528566

That's fine for most people (although the DIY is a PITA) - but I ask
this newsgroup whether anyone has any insight into WHAT is actually
breaking - and - why?
http://www.bimmerfest.com/forums/showthread.php?t=309399

Here is the best (admittedly sketchy) wiring diagram we have so far:
http://www1.picturepush.com/photo/a/12467819/img/12467819.png

[the will]

Blower motor drawing too much amperage taking it out. Change the
blower motor anytime?

[Nate Nagel]

On 03/21/2013 06:55 AM, the will wrote:
> Blower motor drawing too much amperage taking it out. Change the
> blower motor anytime?
>

My thought as well. Have you measured current draw on a new blower
motor and compared it to one that is installed in a car where the FSU
has failed? that would tell you whether there's any merit to this idea
or not.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

[VinnyB]

On Thu, 21 Mar 2013 03:08:09 +0000 (UTC), Bimmer Owner
<donta...@mymail.com> wrote in <kidtio$bco$1...@news.albasani.net> Re
Root cause insight into the common BMW blower motor resistor failures:

>Does anyone have insight into what is the root cause (and repair) of the
>FSU failure that plagues almost every 1997 to 2003 BMW?
> http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994

This is a design feature of BMWs. It's one of many whose purpose is
to economically support BMW dealers with $$ from the fools dumb enough
to buy a BMW.

"A fool and his money are soon parted".

As well they should be.

Enjoy your ride.

[Scott Dorsey]

Nate Nagel <njn...@roosters.net> wrote:
>On 03/21/2013 06:55 AM, the will wrote:
>> Blower motor drawing too much amperage taking it out. Change the
>> blower motor anytime?
>
>My thought as well. Have you measured current draw on a new blower
>motor and compared it to one that is installed in a car where the FSU
>has failed? that would tell you whether there's any merit to this idea
>or not.

My inclination is to do exactly the same thing I do with the cooling system
issues: blame German engineers who seem to believe that their climate is
typical of the entire world.

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure. Put a bigger transistor
in there.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Bimmer Owner]

On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:

> I don't see why it is so hard to unpot one of these things and repair them
> directly, especially if it's a semiconductor failure.
> Put a bigger transistor in there.

Here are pictures from the last half dozen who tried that approach:
http://www2.picturepush.com/photo/a/12470740/img/12470740.jpg
http://www4.picturepush.com/photo/a/12470742/img/12470742.jpg
http://www2.picturepush.com/photo/a/12470745/img/12470745.jpg
http://www4.picturepush.com/photo/a/12470747/img/12470747.jpg
http://www5.picturepush.com/photo/a/12470748/img/12470748.jpg
http://www2.picturepush.com/photo/a/12470750/img/12470750.jpg

Most who try to unpot fail, mainly due to damage caused to the
surface-mount circuit board during the initial mechanical degooping
step.

Those deft few who avoid knocking off the surface-mount components
with the debriding chisel, are left with a badly bruised board,
where some have said they've resoldered solder cracks (see pics).

One problem with "put a bigger xtor" is that nobody on this planet
has produced a decent circuit diagram of the FSU.

Does anyone here have access to an FSU circuit diagram?

[Bimmer Owner]

On Thu, 21 Mar 2013 03:55:47 -0700, the will wrote:

> Blower motor drawing too much amperage taking it out.
> Change the blower motor anytime?

This is an interesting approach, given that the vast majority of
bimmer owners do NOT replace the blower motor - they replace the FSU.

While the blower motor replacement procedure is a major PITA, one
'can' test the leads from the FSU harness connector pins #5 and #1
which are power and ground respectively to the blower motor.

Again, we don't have a circuit diagram, but it has been said that
the blower motor takes about 6 amps (variously, depending on the speed)
but it would take a test jig to test that in operation.

To my knowledge, nobody has created that test jig (although I know
of only one attempt, which failed):
http://www.bimmerfest.com/forums/showthread.php?t=678534&highlight=fsu

It's easy enough to test the resistance of the blower motor though,
and those results have come out at about 0.4 to 0.6 ohms.

It would be expensive to change a blower motor on a whim, so, how
would YOU suggest the blower motor be tested in situ?

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>
>It's easy enough to test the resistance of the blower motor though,
>and those results have come out at about 0.4 to 0.6 ohms.

Static resistance doesn't tell you anything, but operating current measured
with a DMM would tell you a lot.

>It would be expensive to change a blower motor on a whim, so, how
>would YOU suggest the blower motor be tested in situ?

I've never tested one, but I put a drop of turbine oil on the motor bearings
every five years or so. I do the same on the window and seat motors too.

I'd imagine if you listen carefully and have good hearing you can tell if the
motor is binding at all, but many people do not.

[Bimmer Owner]

On Wed, 20 Mar 2013 23:17:36 -0700, jim beam wrote:

> analyze the actual problem - don't just waste money replacing stuff.

That's exactly what we've done - yet - we need help since nobody to
date has figured out HOW to test an FSU that is fried.
http://www.bimmerfest.com/forums/showthread.php?t=678534

Note: It appears to be an active component, but it probably does
dissipate 100W.

[Bimmer Owner]

On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:

> it's cheaper to just buy a new one.

To be clear, that's what 99.99999999% of the BMW owners do.
But that's not the point of this thread.

The point of this thread is to get a handle on WHY they are all
failing.

Specifically, how to figure that out is the question.

[Bimmer Owner]

On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:

> Static resistance doesn't tell you anything, but operating current
> measured with a DMM would tell you a lot.

It 'can' be done, but would require a test jig inserted inline
as the FSU is deeply ensconced under the dash while the blower motor
is even more deeply so.

> I've never tested one, but I put a drop of turbine oil on the
> motor bearings every five years or so.

While that preventive work might be prudent, the sheer effort
to remove the entire dash simply to access the blower motor
would be problematic.

Still, if the problem is that the blower motor is merely using more
current as it gets older, why wouldn't a NEW FSU burn up within a
few weeks of insertion?

[JIMMIE]

On Thursday, March 21, 2013 3:08:09 AM UTC, Bimmer Owner wrote:
> Does anyone have insight into what is the root cause (and repair) of the FSU failure that plagues almost every 1997 to 2003 BMW? http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994 Also, does anyone have an idea HOW TO TEST a "repaired" FSU? The "blower motor resistor", which also goes by FSR (Final Stage Resistor) or by FSU (Final Stage Unit), is known to fry itself in almost every single E46 (3-series), E39 (5-series), and E38 (7-series) BMW. http://www.bimmerfest.com/forums/showthread.php?t=143393 The problem with replacing this ~$100 part is that the new replacement FSU fries itself just as often as the old one did, so you end up repeatedly replacing your fried FSU every few years or so. http://www.bimmerfest.com/forums/showthread.php?t=528566 That's fine for most people (although the DIY is a PITA) - but I ask this newsgroup whether anyone has any insight into WHAT is actually breaking - and - why? http://www.bimmerfest.com/forums/showthread.php?t=309399 Here is the best (admittedly sketchy) wiring diagram we have so far: http://www1.picturepush.com/photo/a/12467819/img/12467819.png

My guess is this is the motor speed control and that it is ANALOG. This means the resistance of the transistor varies with the speed. It gets hotest when the transistor is somewhere between full on and full off. At full on or full off the resistance of the transistor is either nearly infinent or close to being a short. In these conditions not much heat is disipated by it. I would design a pulse width modulated controller. This controls the current to the motor in a digital fashion by switching the power off and on to the transistor is either in the fully off or fully on state. I have seen such circuits on the internet just by googling PWM motor controller. They are very simple to build with a big power FET and an NE555 oscilator also very cheap. Adapting it to the existing controls would be your problem. The googled articles will also tell you a lot more about how and why they work more efficently than an analog controller than I am willing to here.

Jimmie

[Ismo Salonen]

On 03/21/2013 06:04 PM, Bimmer Owner wrote:
> Still, if the problem is that the blower motor is merely using more
> current as it gets older, why wouldn't a NEW FSU burn up within a
> few weeks of insertion?

If the unit is near its limits it might just get very hot and parts
start aging very fast -> semiconductors will just fail after a little
while. The new unit should fail sooner than the old one but who knows
who soon, maybe after a few years. Peugeot's ( and Citroen) used just
one huge pnp darlington which failed quite often , it was working too
near its operating limits.

(just my 2 cents)
ismo

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:
>
>> I don't see why it is so hard to unpot one of these things and repair them
>> directly, especially if it's a semiconductor failure.
>> Put a bigger transistor in there.
>
>Here are pictures from the last half dozen who tried that approach:
> http://www2.picturepush.com/photo/a/12470740/img/12470740.jpg
> http://www4.picturepush.com/photo/a/12470742/img/12470742.jpg
> http://www2.picturepush.com/photo/a/12470745/img/12470745.jpg
> http://www4.picturepush.com/photo/a/12470747/img/12470747.jpg
> http://www5.picturepush.com/photo/a/12470748/img/12470748.jpg
> http://www2.picturepush.com/photo/a/12470750/img/12470750.jpg

These are kind of sloppy jobs. But it's clear there are two TO-3 devices
there which have been removed in all of those photos.

>One problem with "put a bigger xtor" is that nobody on this planet
>has produced a decent circuit diagram of the FSU.

Well, has anyone got docs on that mystery IC there? It's from Elmos
Semiconductor, but it's not a standard Elmos part number on it, so it's
almost certainly a custom, since it doesn't look like anything in their
standard book.

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:
>
>> Static resistance doesn't tell you anything, but operating current
>> measured with a DMM would tell you a lot.
>
>It 'can' be done, but would require a test jig inserted inline
>as the FSU is deeply ensconced under the dash while the blower motor
>is even more deeply so.

I don't know the wiring diagram on that particular model, so I don't know
where you would need to break in to measure just the current of the blower
without anything else. But it does not seem terribly insurmountable,
especially seeing that BMW is very good about breaking everything out into
connectors all over.

>> I've never tested one, but I put a drop of turbine oil on the
>> motor bearings every five years or so.
>
>While that preventive work might be prudent, the sheer effort
>to remove the entire dash simply to access the blower motor
>would be problematic.

Well, that's partly why I drive a 2002 and an E28, everything is much
easier to get to.

>Still, if the problem is that the blower motor is merely using more
>current as it gets older, why wouldn't a NEW FSU burn up within a
>few weeks of insertion?

You would expect that, indeed.

[tm]

"Scott Dorsey" <klu...@panix.com> wrote in message
news:kifmfo$7l$1...@panix2.panix.com...

> Bimmer Owner <donta...@mymail.com> wrote:
>>On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:
>>
>>> Static resistance doesn't tell you anything, but operating current
>>> measured with a DMM would tell you a lot.
>>
>>It 'can' be done, but would require a test jig inserted inline
>>as the FSU is deeply ensconced under the dash while the blower motor
>>is even more deeply so.
>
> I don't know the wiring diagram on that particular model, so I don't know
> where you would need to break in to measure just the current of the blower
> without anything else. But it does not seem terribly insurmountable,
> especially seeing that BMW is very good about breaking everything out into
> connectors all over.
>

Just measure the battery current with and without the blower running.

Turn every thing else off.


QED

[Bimmer Owner]

On Thu, 21 Mar 2013 16:59:01 -0400, tm wrote:

> Just measure the battery current with and without the blower running.
> Turn every thing else off.

That's a pretty good idea.

Of course, it's impossible to turn everything off, as the computer
won't go to sleep for 16 minutes after the car is shut and armed,
but, still - with the blower consuming something like 5 or 6 amps,
we should be able to measure at least that.

The problem, even with the car's additional electronics powered up,
is HOW MUCH of a difference are we expecting between an older blower
motor current draw and a new one?

Are we looking for a 1 amp difference, for example?

[mrob...@att.net]

Followups set to sci.electronics.repair .

In sci.electronics.repair Bimmer Owner <donta...@mymail.com> wrote:
> Does anyone have insight into what is the root cause (and repair) of
> the FSU failure that plagues almost every 1997 to 2003 BMW?

At a guess, one or both of the big power transistors that are inside the
FSU are failing. If the failure is that the blower motor doesn't run at
all, they are probably failing open. If the failure is either that the
blower motor runs at maximum speed, or a fuse blows, then they are
probably failing shorted. The blower motor probably draws more current
as it ages, and it may eventually be exceeding the power-handling
capability of the transistor(s). When the motor is switched off, it may
also generate a bit of a voltage spike, which may be above the voltage
rating of the transistor(s).

A possible solution is to replace the transistor(s) with ones with a
higher power rating in the same package. Another approach is to improve
the heat-sinking, maybe by adding metal to the existing fins. Or, cut
off the existing fins, bolt it to a huge slab of metal, and relocate the
entire thing away from the blower duct.

As a crutch, you could drop the voltage to the FSU a little bit. This
would slow down the blower, but also might tend to keep the voltages
and currents down to what the transistors can handle. You would need
to know the maximum current you would expect the FSU to draw; this
probably happens when the charging system voltage is at is maximum,
the blower motor is stone cold, and you turn it from "off" to "max".
Then, buy a big rectifier diode with a rating of a few amps more than
that, and splice it in to the power wire to the FSU. This will drop
the voltage by a volt or two all the time. Or, you could put a power
resistor in line instead; this will cause a variable voltage drop
depending on how much power the FSU and blower is drawing at the time.

Keep in mind that in the winter, keeping the windshield clear is a
safety function, so don't drop the blower speed too much.

> Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The tricky part depends on the nature of the control signal to the FSU.
If it's a simple analog voltage, that is easy to generate on the bench
with a potentiometer. If it's some kind of digital bus (CAN?), it is
*possible* to generate that on the bench, but it's probably easier to
get the dashboard heater control out of a junked car and let it generate
the signal.

To load the FSU, you can either use a power resistor that draws about
the same amount of current as the blower motor on "high" (a headlight
lamp might qualify), or an actual blower motor. The resistor will be
"better behaved" than a real motor.

For a power supply, it depends on how much current the blower motor
needs. You can get relatively inexpensive 13.8-volt power supplies in
ranges up to several amps, designed for running "12 V" equipment on the
bench. Samlex is one manufacturer but there are others. If it needs
more than 10 A or so, it's probably cheaper to just use a real car
battery and charge it when it's not being used.

You should probably arrange it so that there is some air blowing on the
FSU under test. If you are using a real blower motor, you can make a
duct out of cardboard. If not, use something like a 12 V computer case
fan to move a little air across the FSU.

It may also be interesting to have some kind of thermometer on the FSU
case while it is under test.

A good way to figure out what the FSU is actually doing is to probe a
working car with an oscilloscope. This will show you immediately how
the FSU is controlling the blower motor speed, as well as what the
control signal looks like. You can stick a straight pin *through* the
wire insulation as a test point, and then seal up the hole with
electrical tape or silicone sealant.

As has been mentioned, it would be also interesting to cut one of the
blower wires and measure the current drawn by the blower motor. For
extra credit, do this on a new car (or a newly-installed blower motor)
and then compare to a blower motor in a car that has just had its FSU
fail.

> The problem with replacing this ~$100 part is that the new replacement
> FSU fries itself just as often as the old one did, so you end up
> repeatedly replacing your fried FSU every few years or so.

On one hand, you would like stuff not to break. On the other hand,
spending $100 every two or three years on a car that starts around
$36,000 new is maybe not out of the realm of possibility. (Perspective:
that's one tire or 25 to 30 gallons of gas.)

These cars are apparently sold worldwide. If the FSUs sell for cheaper
in a lower-cost country, enough to offset shipping and taxes, import a
box full of them and make money. :)

Matt Roberds

[Ashton Crusher]

The simple answer is that they are under-designed for the conditions
under which they apparently are regularly subject to.

[Ashton Crusher]

If one replaces one of these perhaps it would be advisable to put a
fuse in the blower motor lines (it sounds like those can be gotten to
easily unlike the motor itself). If it's being blown by intermittent
high current draws the fuse could protect the $100 FSU. Another
option would be, at least for those who can live without the highest
blower setting and who think excess current draw is the culprit, would
be to put a power resistor in the blower motor line to limit the
current a bit. On the cheap pedestrian cars I drive the whole speed
control is just a trio of power resistors placed in the air flow to
help cool them. If they burn out (which is rare) they can sometimes
be fixed with a pop rivet.

[Bimmer Owner]

On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:

> If it's being blown by intermittent high current draws the
> fuse could protect the $100 FSU.

That's an interesting idea. The FSU supposedly consumes the
most power when the blower motor is set to the LOW settings
(simply because it has to dissipate the power as heat), so,
we could prevent excess current by fusing... say with a 10A
fuse, the blower motor (which is said to consume 5 to 6 A).

[Bimmer Owner]

On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:

> If the failure is that the blower motor doesn't run at all, they are
> probably failing open. If the failure is either that the blower motor
> runs at maximum speed, or a fuse blows, then they are probably failing
> shorted.

Actually, I was remiss in not stating that the blower motor generally
fails by acting weirdly, often said to "have a mind of its own", and,
most often by a parasitic current draw overnight that kills the battery.

[Mark]

> > If the failure is that the blower motor doesn't run at all, they are
> > probably failing open.  If the failure is either that the blower motor
> > runs at maximum speed, or a fuse blows, then they are probably failing
> > shorted.
>

i guess they call replacing a simple resistor with a bunch of
transistors.... "progress"

i'd replace the module with a bunch of power resistors and maybe a PTC
(self resetting) fuse

Mark


Mark

[Bimmer Owner]

On Thu, 21 Mar 2013 15:16:46 -0400, Scott Dorsey wrote:

> there are two TO-3 devices there which have been removed
> in all of those photos.

I don't know what a "TO-3" device is, but nobody removed anything
in those photos other than the goop that covered the circuit board.

> has anyone got docs on that mystery IC there? It's from Elmos
> Semiconductor, but it's not a standard Elmos part number on it

Focusing just on that Elmos Semiconductor AG IC from this thread:
http://www.bimmerfest.com/forums/showthread.php?t=309399
It looks like the PN is ELMOS, 10901D, 667A 1302A

It might be a generic or a special chip; I can't find it on the web:
http://www.elmos.com/produkte/automotive/motor-control/dc-motor-ics.html

[Bimmer Owner]

On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:

> It may also be interesting to have some kind of thermometer

> on the FSU case ...

That seems like an EXCELLENT idea, if we can put some kind
of temperature indicator in the FSU tines, then we can observe
what the temperature is in situ - which might tell us something
about what is overheating these things (assuming heat is the culprit).

[cl...@snyder.on.ca]

On Thu, 21 Mar 2013 16:59:01 -0400, "tm" <No_on...@white-house.gov>
wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message
news:kig343$pdf$2...@news.albasani.net...

Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.
PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

Another place you could measure the current is by putting an ammeter in
place of the blower motor fuse.


tm

[cl...@snyder.on.ca]

So the crafty germans are using a high tech solid state resistor
instead of a PWM speed controller???

If I had one and it blew I think I'd be designing a PWM controller to
take it's place. Need to find out what kind of signal the controller
expects, but that shouldn't be too difficult.

[tra...@optonline.net]

On Mar 21, 5:58 pm, Ashton Crusher <d...@moore.net> wrote:
> On Thu, 21 Mar 2013 16:00:13 +0000 (UTC), Bimmer Owner
>

> <dontask...@mymail.com> wrote:
> >On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>
> >> it's cheaper to just buy a new one.
>
> >To be clear, that's what 99.99999999% of the BMW owners do.
> >But that's not the point of this thread.
>
> >The point of this thread is to get a handle on WHY they are all
> >failing.
>
> >Specifically, how to figure that out is the question.
>
> The simple answer is that they are under-designed for the conditions
> under which they apparently are regularly subject to.

That isn't necessarily the case. For example,t hey could be correctly
designed, rated for the application, etc but have a manufacturing
defect in just one of the components.

A better questions is why BMW apparently doesn't give a damn
to do the failure analysis to find out what's wrong. I have a friend
who has an X5 and had this problem with the blower resistors.
Even worse, the only symptom was it was draining the battery
and it took a huge number of hours to track it down.

While you're all wondering about that problem, might as well
add the fancy aux radiator fan to the list. This car had that go
and now the replacement one has failed again. And the
symptom there is, again, it drains the battery even when the
car is off. That fan is a real POS. Instead of just a simple
fan motor, it's a fan that's variable speed, driven by a PWM
signal. So, instead of just a motor, that fan sitting in front
of the hot radiator has electronics in it. A real genius of a
design. And for what? Like the fan can't just be on or off?
Only reason I can think of is that they want to save a few
watts of power to try to get better fuel economy. And for
that their customers get to shell out $500 for a new fan
every few years.

[tra...@optonline.net]

On Mar 21, 8:08 pm, cl...@snyder.on.ca wrote:
> On Thu, 21 Mar 2013 22:54:59 +0000 (UTC), Bimmer Owner
>

The dopes at BMW aren't any better at PWM's either.
They use a PWM signal to control the aux fan on the radiator.
You, know, the one that comes on if the cooling temp gets
too high or the AC is on, etc. Apparently just a simple on/off
motor wasn't good enough. So they made another one of
their German electronic miracle gadgets that's part of the
fan motor. That's right, electronics sitting right next to the
hot radiator.....

On the TV show All in The Family, the meathead was arguing
about Nixon and Watergate with Archie. Archie told the meathead
that Nixon's mistake was when it involved electronics, ie bugging,
taping, etc, that he should have used the Japanese, not Germans,
ie Haldeman, Ehrlichman, etc. I think Archie was on to something.

[bob haller]

On Mar 20, 11:08 pm, Bimmer Owner <dontask...@mymail.com> wrote:
> Does anyone have insight into what is the root cause (and repair) of the
> FSU failure that plagues almost every 1997 to 2003 BMW?

>  http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d...

>
> Also, does anyone have an idea HOW TO TEST a "repaired" FSU?
>

> The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
> or by FSU (Final Stage Unit), is known to fry itself in almost every single
> E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
>  http://www.bimmerfest.com/forums/showthread.php?t=143393
>

> The problem with replacing this ~$100 part is that the new replacement FSU
> fries itself just as often as the old one did, so you end up repeatedly
> replacing your fried FSU every few years or so.

>  http://www.bimmerfest.com/forums/showthread.php?t=528566
>
> That's fine for most people (although the DIY is a PITA) - but I ask
> this newsgroup whether anyone has any insight into WHAT is actually
> breaking - and - why?
>  http://www.bimmerfest.com/forums/showthread.php?t=309399
>
> Here is the best (admittedly sketchy) wiring diagram we have so far:
>  http://www1.picturepush.com/photo/a/12467819/img/12467819.png

I had a dodge caravan that fried its heater AC motor speed control
resistor repeatedly....

the connector to the wiring harness detoriates from the high current
and the voltage drop causes the connector to heat up and the entire
assembly fails.

Oddly enough I repair roll laminators that apply plastic film to paper
think menus:)

laminators experience similiar failures so I did the following.

Purchased a new resistor block, soldered wires on all the connectors
putting a heavy wire on each one.... Put a pigtail on each one.
Installed resistor block. Its screwerd to the fire wall.

Cut the plug assembly off the harness, stripped all wires, twisted
them together and installed wire nuts on each one.

had the van for years with zero problems for this part:)

[Scott Dorsey]

All the standard Elmos part numbers begin with an E.

My guess is that the number on the chip is 10901D and that the other
two numbers are date and batch codes.

[Bimmer Owner]

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

> Just put your ammeter into the heater blower fuse connector and you
> get the current of the blower motor.

That's an interesting idea.

http://www3.picturepush.com/photo/a/12475041/img/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/12475043/img/12475043.jpg

[Ashton Crusher]

Hmm, it did look like it had quite a heat sink. I had assumed it used
PWM to change speed, which should not generate much heat but my
assumption might be wrong (or my understanding of PWM...) A solid
state design that gets hot on purpose seems like a poor design to me.

[VinnyB]

On Thu, 21 Mar 2013 16:07:23 -0700 (PDT), Mark <mako...@yahoo.com>
wrote in
<7ac8d06f-c707-41a9...@l9g2000yqp.googlegroups.com> Re
Re: Root cause insight into the common BMW blower motor resistor
failures:

Why not just buy a Toyota and save yourself a lot of problems in the
future.

[tra...@optonline.net]

On Mar 21, 10:25 pm, klu...@panix.com (Scott Dorsey) wrote:

If you google for 10901D it comes back with hits to
Chinese chip brokers that show it as an Elmos 16
pin surface mount chip. Which is consistent with what's
in the picture of the failed module, it has 16 pins.
But I could not find any data sheet on the part either.

[Bimmer Owner]

On Fri, 22 Mar 2013 05:20:37 -0700, tra...@optonline.net wrote:

> If you google for 10901D it comes back with hits to Chinese chip brokers
> that show it as an Elmos 16 pin surface mount chip.

I found the same. The chip is listed here:
http://www.jotrin.com/product/parts/10901D

But there is no datasheet there.

[Bimmer Owner]

On Fri, 22 Mar 2013 05:20:37 -0700, tra...@optonline.net wrote:

> If you google for 10901D it comes back with hits to Chinese chip brokers
> that show it as an Elmos 16 pin surface mount chip.

I found a Russian language description of it here:
http://tinyurl.com/crg2sms
http://kazus.ru/schematics/electrical-engineering/search/go/?text=%D0%C5%C3%D3%CB%DF%D2%CE%D0%20ELMOS%2010901D&nohistory=1&h=1

[Bimmer Owner]

On Fri, 22 Mar 2013 12:31:09 +0000, Bimmer Owner wrote:

> I found a Russian language description of it here:
> http://tinyurl.com/crg2sms

Here is a google translation

REGULATOR ELMOS 10901D
Car Voltage Regulator
Category: Car
Source: Radioland country Electronics
Temperature controller cabin air KAMAZ

Source: Plans radiokonstruktsy
Simple Temperature compensated voltage regulator.
Controller together with thyristor-transistor electronic ignition unit
with a long spark, ensuring the rapid start-ups at various operating
conditions, allowed to increase battery life of up to nine years.

Source: For the life of a soldering iron ...
Regulator for automotive windshield

Source: MASTER KIT
The controller measures the wiper-this control is designed to use regular mode switch blades and is contactless.

Source: For the life of a soldering iron ...
Temperature compensated voltage regulator device in some ways superior designs.
The controller can be used as a universal device is suitable not only for
mounting on any car, but everywhere, where the generator rotor speed is
variable (eg, wind power).
Choose the appropriate control elements, it can be easily adapted to work
with any voltage (up to 400V) and excitation current (tens of amperes).

Source: For the life of a soldering iron ...
Voltage regulator 2012.3702, 22.3702, 221.3702

Source: For the life of a soldering iron ...
Voltage regulator 201.3702

Source: For the life of a soldering iron ...
Voltage Regulator 13.3702

Source: For the life of a soldering iron ...
Voltage regulator RR132A, 1112.3702

[Bimmer Owner]

On Fri, 22 Mar 2013 12:31:09 +0000, Bimmer Owner wrote:

> I found a Russian language description of it here:

Googling for the Russian text, I find they appear to have
the same problem with the same FSU over here:
http://www.elektroda.pl/rtvforum/viewtopic.php?p=8838466#8838466

[carson ridder]

On Fri, 22 Mar 2013 05:07:17 -0500, VinnyB wrote:

> Why not just buy a Toyota and save yourself a lot of problems
> in the future.

Might be a good idea! :)

My E46 hedgehog cooked itself twice in 4 years!
http://www.diablo944.co.uk/Hedgehogimageset.pdf

[Nate Nagel]

They haven't sold the Supra here in ages :(

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

[tra...@optonline.net]

On Mar 21, 11:22 am, Bimmer Owner <dontask...@mymail.com> wrote:
> On Thu, 21 Mar 2013 03:55:47 -0700, the will wrote:
> > Blower motor drawing too much amperage taking it out.
> > Change the blower motor anytime?
>
> This is an interesting approach, given that the vast majority of
> bimmer owners do NOT replace the blower motor - they replace the FSU.
>
> While the blower motor replacement procedure is a major PITA, one
> 'can' test the leads from the FSU harness connector pins #5 and #1
> which are power and ground respectively to the blower motor.
>
> Again, we don't have a circuit diagram, but it has been said that
> the blower motor takes about 6 amps (variously, depending on the speed)
> but it would take a test jig to test that in operation.
>
> To my knowledge, nobody has created that test jig (although I know
> of only one attempt, which failed):http://www.bimmerfest.com/forums/showthread.php?t=678534&highlight=fsu
>
> It's easy enough to test the resistance of the blower motor though,
> and those results have come out at about 0.4 to 0.6 ohms.
>
> It would be expensive to change a blower motor on a whim, so, how
> would YOU suggest the blower motor be tested in situ?

If it's just a typical DC motor with two leads, apply 12V and
it should run full speed. You could also measure how many amps it
draws when running. That is, IF it's just an ordinary motor.

[cl...@snyder.on.ca]

Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult

[tra...@optonline.net]

> lives so difficult- Hide quoted text -
>
> - Show quoted text -

It's kind of amazing the fuse is 40 amps, no? I mean a 1 hp
motor draws ~1500W And this heater blower is 480W?
Seems like a lot to me.....

[cl...@snyder.on.ca]

On 22 Mar 2013 13:46:59 GMT, carson ridder

But anyone who thinks they are somebody or something needs to own at
least ONE weiner wagon - mabee two or 3 - one of each major brand -
MB, BMW, and Audi - and perhaps a Porsche - just to prove they are not
invulnerable and all powerfull. Either one of them can take a guy
down a notch pretty quickly.

[Nate Nagel]

Not unless you want to become addicted and need to drive kraut burners
for the rest of your life. I and several friends have unfortunately
fallen prey to this disease and our wallets have suffered as a result.

[R. Mark Clayton]

Have you got a link to these "common problems" you keep posting about?

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kidtio$bco$1...@news.albasani.net...

> Does anyone have insight into what is the root cause (and repair) of the
> FSU failure that plagues almost every 1997 to 2003 BMW?

> http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994

=========

> Almost every BMW E39 (5-series) and E38 (7-series) and E46 (3-series)
> has shorts that develop in the trunk wiring loom - all in the same spot!

[Clive]

In message
<acc3106a-224e-4a7c...@v8g2000yqe.googlegroups.com>,
"tra...@optonline.net" <tra...@optonline.net> writes

> Instead of just a simple
>fan motor, it's a fan that's variable speed, driven by a PWM
>signal.

If by PWM you mean pulse width modulation, then it would allow for
variable speed, but a DC motor is an inductive load and is not sensibly
controlled by such a system unless there is something in the circuit to
allow the peak voltage generated by the motor at pulse cut of to be
shunted to earth.
--
Clive

[tra...@optonline.net]

On Mar 23, 6:48 am, Clive <cl...@yewbank.demon.co.uk> wrote:
> In message
> <acc3106a-224e-4a7c-a17e-69cfe3e13...@v8g2000yqe.googlegroups.com>,
> "trad...@optonline.net" <trad...@optonline.net> writes> Instead of just a simple

> >fan motor, it's a fan that's variable speed, driven by a PWM
> >signal.
>
> If by PWM you mean pulse width modulation, then it would allow for
> variable speed, but a DC motor is an inductive load and is not sensibly
> controlled by such a system unless there is something in the circuit to
> allow the peak voltage generated by the motor at pulse cut of to be
> shunted to earth.
> --
> Clive

That "something" could be as simple as a diode. PWM is
commonly used to vary the power to a motor. BMW, for
example, uses it on the aux fan motor of the X5. And I
would suspect that it's also used for the blower motor
because you wind up wasting a lot less power that way.
And every little bit of power saved adds up and effects MPG.

[tra...@optonline.net]

On Mar 22, 7:42 pm, "R. Mark Clayton" <nospamclay...@btinternet.com>
wrote:

> Have you got a link to these "common problems" you keep posting about?
>

> "Bimmer Owner" <dontask...@mymail.com> wrote in message

>
> news:kidtio$bco$1...@news.albasani.net...
>
> > Does anyone have insight into what is the root cause (and repair) of the
> > FSU failure that plagues almost every 1997 to 2003 BMW?

> >http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d...

>
> =========
>
>
>
> > Almost every BMW E39 (5-series) and E38 (7-series) and E46 (3-series)

> > has shorts that develop in the trunk wiring loom - all in the same spot!- Hide quoted text -

>
> - Show quoted text -

I don't have a link, but we had the blower resistor widget
go on an X5 here. And the aux cooling fan motor has gone
twice. There are plenty of threads online about many people having
those problems. Oh, and don't forget the
nice X5 feature where the cable that they use to hold up the
windows snaps, sending the window crashing down inside
the door, breaking it into a million pieces. Had that happen
twice too, once while the car was just sitting in the driveway.
Other time was driving down the highway.

Then there are their defective rubber parts. Like the boot on
the intake manifold that cracks in just a few years. Or the
CV joint boots. I've had lots of cars with CV boots and
only on the X5 do they fail every 20K miles. I've seen Honda CRVs
that went 200K miles with no failure.

[Clive]

In message
<b15e9629-0f65-4f53...@7g2000yqy.googlegroups.com>,
"tra...@optonline.net" <tra...@optonline.net> writes

>That "something" could be as simple as a diode. PWM is
>commonly used to vary the power to a motor. BMW, for
>example, uses it on the aux fan motor of the X5. And I
>would suspect that it's also used for the blower motor
>because you wind up wasting a lot less power that way.
>And every little bit of power saved adds up and effects MPG.

I agree with all you say.
--
Clive

[Clive]

In message <kif8k1$ddg$2...@news.albasani.net>, Bimmer Owner
<donta...@mymail.com> writes

>It's easy enough to test the resistance of the blower motor though,
>and those results have come out at about 0.4 to 0.6 ohms.

Motors are not just a resistive load though.
--
Clive

[cl...@snyder.on.ca]

On Sat, 23 Mar 2013 10:48:27 +0000, Clive <cl...@yewbank.demon.co.uk>
wrote:

PWM is the most common method of controlling the speed of DC motors -
a flywheel diode is part of the "system" to handle the inductive
kick-back. Virtually all battery operated variable speed power tools
use PWM. So do virtually all electric bicycles with brush motors and
the vast majority of electric forklifts.

In fact, just about any application of a brush type DC motor that
requires reasonable speed control has switched to PWM control of some
sort over the last 20 years, including power wheel chairs (except
those using 3 phase brushless motors)

[Michael A. Terrell]

Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week. :(

[Michael A. Terrell]

Bimmer Owner wrote:
>
> On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:
>
> > If it's being blown by intermittent high current draws the
> > fuse could protect the $100 FSU.
>
> That's an interesting idea. The FSU supposedly consumes the
> most power when the blower motor is set to the LOW settings
> (simply because it has to dissipate the power as heat), so,
> we could prevent excess current by fusing... say with a 10A
> fuse, the blower motor (which is said to consume 5 to 6 A).

It should generate less heat at low speeds, if it is PWM.

[cl...@snyder.on.ca]

Or just get the special tester that is made to plug into the
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.

[Michael A. Terrell]

tm wrote:
>
> "Bimmer Owner" <donta...@mymail.com> wrote in message

> news:kig343$pdf$2...@news.albasani.net...

> > On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:
> >
> >> If it's being blown by intermittent high current draws the
> >> fuse could protect the $100 FSU.
> >
> > That's an interesting idea. The FSU supposedly consumes the
> > most power when the blower motor is set to the LOW settings
> > (simply because it has to dissipate the power as heat), so,
> > we could prevent excess current by fusing... say with a 10A
> > fuse, the blower motor (which is said to consume 5 to 6 A).
> >
>

> Are you sure it is not already a pulse width regulator? Those transistors
> look like they are TO-220 packages, not TO-3.


I've seen 20W power resistors in TO-220 packages.


> PWM has been around longer than SMT parts.
>
> Maybe it is transients from the motor that are causing the failures.
>
> Another place you could measure the current is by putting an ammeter in
> place of the blower motor fuse.
>
> tm

[Michael A. Terrell]

Is that cheaper than roll your own?

[Scott Dorsey]

Michael A. Terrell <mike.t...@earthlink.net> wrote:

>tm wrote:
>>
>>
>> Are you sure it is not already a pulse width regulator? Those transistors
>> look like they are TO-220 packages, not TO-3.
>
> I've seen 20W power resistors in TO-220 packages.

It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).

But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.

>> PWM has been around longer than SMT parts.
>>
>> Maybe it is transients from the motor that are causing the failures.

This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.

If it's a RoHS soldering issue, though, I would not be surprised.

[Jamie]

A few car manufacturers use resistor wire in the harness leading to
the motor connection at the blower box.

This lowers the Q significantly giving you a voltage drop of course,
but it also reduces electrical noise and helps suppress the wheeling
voltages.

Blower motors in this case are normally designed to operate lets say
8 volts for example, for full RPM.

I learned this years ago when going through the pain of removing the
blower in an air box of a Chrysler product, only to find there was
nothing wrong with the motor. Symptoms led on to the fact there was
since the output of the speed control circuit was alive and happy but
no obvious connection to the motor. If I had unplugged it from the air
box before pulling that all apart, I would of noticed it.

The problem was the resistor wire in the harness which had open at the
crimp point, also in the harness.

Jamie

[cl...@snyder.on.ca]

On Sun, 24 Mar 2013 02:28:00 -0400, "Michael A. Terrell"

Definitely not, if you already have a multimeter - but it is easier
for the guys who can't figure out how to do it without butchering the
wiring harness.

[Michael A. Terrell]

That type shouldn't be allowed to own any tools. They generally do
more damage than good. If they do get something to work, it rarely lasts
because they have no clue what because the problem.

I've seen too many vehicles that some idiot cut and patched back
together. One stepvan I bought years ago had a damaged harness and I
talked them down almost $1000 on the price. It was coming off lease
from a fleet, and they wanted to fix it themselves. i pointed out that
if they could repair it properly, it wouldn't be in that condition.

[Michael A. Terrell]

Scott Dorsey wrote:
>
> Michael A. Terrell <mike.t...@earthlink.net> wrote:
> >tm wrote:
> >>
> >>
> >> Are you sure it is not already a pulse width regulator? Those transistors
> >> look like they are TO-220 packages, not TO-3.
> >
> > I've seen 20W power resistors in TO-220 packages.
>
> It does indeed look like a TO-220 from the pin spacing (since there are no
> actual transistors in the photos, just spots from which they were removed).

All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.

> But if it had been a PWM device, there would have been some filtering in
> there, inductors and capacitors to keep the noise from getting into the
> power lines. Designing clean and quiet PWM controllers is not quite as
> trivial as some folks have made it out to be.

Have you looked at the National Semiconductor (Now part of T.I)
'Simple Switcher' series of controllers? Generally only one inductor
and a couple small electrolytics. A lot simpler than older designs, and
little noise because of the small footprint.

> >> PWM has been around longer than SMT parts.
> >>
> >> Maybe it is transients from the motor that are causing the failures.
>
> This is possible, if it is the transistors that are failing. I don't see
> any big protection diodes in there either.
>
> If it's a RoHS soldering issue, though, I would not be surprised.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

[Bimmer Owner]

On Fri, 22 Mar 2013 15:04:39 -0400, clare wrote:

>>So that's a possibility; but you'd have to cut the wires.
>> http://www5.picturepush.com/photo/a/12475043/img/12475043.jpg
> Why would you have to cut the wires????
> Simply remove the fuse and connect the ammeter. You guys make your
> lives so difficult

The 40 amp fuse is barely accessible (as can be seen from the photos).
It's not even easy to pull the fuse & even harder to replace it.
So, all I was saying was that it's actually rather difficult to insert
test leads into the empty fuse #F76 fuse holder.

I'd wager it 'can' be done - it's just going to take an hour or so
to get the leads in place.

[Bimmer Owner]

On Sat, 23 Mar 2013 22:27:41 -0400, Michael A. Terrell wrote:

> Take a blown fuse and use it for a test connector

That's an idea.

[Bimmer Owner]

On Sun, 24 Mar 2013 09:24:13 -0400, Scott Dorsey wrote:

> It does indeed look like a TO-220 from the pin spacing (since there are no
> actual transistors in the photos, just spots from which they were removed).

I doubt anything was removed since all the authors of those pictures
are expressly NOT trying to remove anything.

Those round metal "dots" in the pictures are the five pin connectors
of the harness connector.

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kiprq6$q7l$1...@news.albasani.net...

So go back to measuring at the battery terminals. Do you have or can you
borrow a clamp on DC ammeter? They are great for this sort of problem. You
don't even lose any skin that way.

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kiprvs$q7l$3...@news.albasani.net...

Are there any other pictures of the module showing if or where the
transistors are attached to the heat sink?

Has anyone ever fully dissected the unit so you can see what is under the PC
board? Maybe an X-ray from several angles done at the dentist?

[cl...@snyder.on.ca]

Bet I can do it in less than half an hour - without the MaxiTester
and in about 5 or 10 minutes with it.

[Bimmer Owner]

On Mon, 25 Mar 2013 09:42:51 -0400, Michael A. Terrell wrote:

> All those photos only show one side. I full reverse engineering
> should be done to draw a full schematic but I've never had my hands on
> that module. It would probably take a couple of them, because ot the
> potting.

These photos show both sides.
http://www.bimmerfest.com/forums/showthread.php?t=309399

Nothing was removed, so I can't figure out WHAT you guys are
saying is the transistor removed.

Can you circle one of these pictures to show WHERE you think
something was removed?

http://www.bimmerfest.com/forums/attachment.php?attachmentid=367580&d=1363957253
http://www.bimmerfest.com/forums/attachment.php?attachmentid=363800&stc=1&d=1361831815
http://www.bimmerfest.com/forums/attachment.php?attachmentid=363808&stc=1&d=1361837887

[Bimmer Owner]

On Fri, 22 Mar 2013 08:37:14 -0700, tra...@optonline.net wrote:

> If it's just a typical DC motor with two leads, apply 12V and
> it should run full speed. You could [then] measure how many amps
> it draws when running.

That makes a lot of sense!

Plus, it's easier to hook up leads to the harness connector than it
is to get a DMM lead on the impossibly hard-to-get-to 40Amp Fuse F76 for
the blower motor.

[Bimmer Owner]

On Fri, 22 Mar 2013 23:42:00 +0000, R. Mark Clayton wrote:

> Have you got a link to these "common problems" you keep posting about?

Of course. Nothing I've ever written is not well documented.

I'm not sure "which" common problem you're asking about, so, here is
just a sample of the most-common problems that afflict almost every
BMW E39, E38, and E46 (I'm sure there are others but I'm only familiar
with those models that use the M54 engine).

http://www.bimmerfest.com/forums/showpost.php?p=6097104&postcount=46

Behr cooling system leaking
Plastic DISA valve breaking & destroying the engine
Cluster pixel tape lifting
MID pixel tape lifting
Hella PBT headlight adjusters breaking
Power steering cap & hose leaking
Trunk wiring loom fraying
CCV clogging
Bosch ABS control module frying
Cupholders breaking
I6 VANOS seals deteriorating
V8 valley pan gaskets leaking
GKR/BMW/Valeo FSU/FSR dying
Thrust arm bushings leaking
Ambient temperature sensor breaking
Window regulators breaking
Vapor barrier adhesive leaking
Jack pads falling off
Windshield cover molding crumbling
Driver's seat control switch breaking
Rear center brakelight socket melting
Seat cables fall out causing seat twist
Windshield washer tanks & pumps leaking
BMW roundel paint chipping
Vent trim corner cracking & wood trim varnish cracking
Rear center brake light socket melting

Note: The reference above has detailed links to EACH of these topics above.

[Bimmer Owner]

On Sat, 23 Mar 2013 07:20:44 -0700, jim beam wrote:

> serious question - why did you buy it?

As for me, I fell sway to all the people saying how great the bimmer was.

It was only after I owned it, that I realized that BMW engineers knew
how to design a suspension and a drive train, but they had no idea
how to build a machine.

To their credit, some people say it's not the engineers fault as
they probably know by now that every single Bosch 5.7 ABS control
module fried in every one of the vehicles it was placed in, and that
the final stage unit cooked itself to death in every single BMW it
was ever placed in, and that the 2-bar plastic cooling system
sprang a leak on almost every single BMW ever built, etc.

In fact, there's absolutely NO WAY BMW can't know about these
egregious engineering flaws. So, the common conclusion is that
their customers don't care - so why should they.

To me, it smacks of 3rd-grade engineering from BMW, so, that's why
I, for one, am amazed (being an owner myself), how sophomoric BMW
engineering really is.

Disclaimer: Yet, the drive train is phenomenal!

[Bimmer Owner]

On Mon, 25 Mar 2013 12:26:52 -0400, clare wrote:

>>I'd wager it 'can' be done - it's just going to take an hour or so
>>to get the leads in place.
> Bet I can do it in less than half an hour - without the MaxiTester
> and in about 5 or 10 minutes with it.

I'd be very happy to see pictures of the test leads in situ
because I personally tried (and succeeded) in getting the 40
amp blower motor fuse F76 out and back in, but I wouldn't
want to do it more than once in my life.

From memory, here's what I did:
. I moved the passenger front seat as far back as I could
. I lowered the passenger front seat back as far back as it goes
. I removed the ignition key and disconnected the battery negative lead
. I removed the panel from the bottom of the glovebox
. I removed the Phillips screw and panel off to the passenger left kneecap
. I lay upside down on the flattened passenger seat, head in the footwell
. I located the general module III (GMIII)
. With my arms bent wildly arms over my head, I disconnected harness connectors
. The first enigmatic connector was the white connector X332
. The next diabolical connector was the small black X253
. And the last puzzling connector was the large black X254
. By now, I could slightly see the yellow 40 & red 50 amp fuses F76 & F77
. With a flathead 1/8" screwdriver, I lifted the yellow fuse F76 up & out
. That took about an hour or three.
. Putting the fuse back was even harder than removing it

[Bimmer Owner]

On Mon, 25 Mar 2013 12:04:20 -0400, tm wrote:

> Has anyone ever fully dissected the unit so you can see what is under the PC
> board? Maybe an X-ray from several angles done at the dentist?

All I have are the following:

[cl...@snyder.on.ca]

If the engine desnt burn to the ground due to oil leaks, or overheat
or run out of oil, because of all the problems with "ancilliary
systems"

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>
>Can you circle one of these pictures to show WHERE you think
>something was removed?
>
>http://www.bimmerfest.com/forums/attachment.php?attachmentid=367580&d=1363957253

Okay, notice on the lefthand photo, there are two sets of three solder joints
on the lefthand side of the board, which show signs of recent rework. There
are TO-220 transistors attached to them, which are behind the board and you
cannot see.

On the righthand photo the board is reversed... you can see two sets of three
holes on the righthand side of the board which is where those TO-220
transistors were attached. You can see that they overheated the board and
lifted pads in the process too.

But you cannot in either of these photos see the transistors or what the part
number on the face of them is. Knowing what kind of transistors are used
will go far toward explaining some possible failure modes.

[tra...@optonline.net]

On Mar 25, 2:55 pm, klu...@panix.com (Scott Dorsey) wrote:

> Bimmer Owner  <dontask...@mymail.com> wrote:
>
>
>
> >Can you circle one of these pictures to show WHERE you think
> >something was removed?
>

> >http://www.bimmerfest.com/forums/attachment.php?attachmentid=367580&d...

>
> Okay, notice on the lefthand photo, there are two sets of three solder joints
> on the lefthand side of the board, which show signs of recent rework.  There
> are TO-220 transistors attached to them, which are behind the board and you
> cannot see.
>
> On the righthand photo the board is reversed... you can see two sets of three
> holes on the righthand side of the board which is where those TO-220
> transistors were attached.  You can see that they overheated the board and
> lifted pads in the process too.
>
> But you cannot in either of these photos see the transistors or what the part
> number on the face of them is.  Knowing what kind of transistors are used
> will go far toward explaining some possible failure modes.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

Maybe it's time to look at this thing like gas and brakes...
You put gas in, you go so far. You put one of these
blower modules in and you go for a few years again.
It's not like they are a $500 or $1000 puter. Don't they
cost like $50? I mean how much is time worth trying
to reverse engineer it.....

[tm]

"Scott Dorsey" <klu...@panix.com> wrote in message
news:kiq6i6$k62$1...@panix2.panix.com...

Yes, what Scott said. Where are the two transistors that were soldered in
the pair of three holes on the right of the right photo.

[dizzy]

I must be lucky. My 2000 323 has had only one of the above "failures"
- leaky power-steering hoses.

[Bimmer Owner]

On Mon, 25 Mar 2013 14:55:02 -0400, Scott Dorsey wrote:

> Okay, notice on the lefthand photo, there are two sets of three solder joints
> on the lefthand side of the board, which show signs of recent rework. There
> are TO-220 transistors attached to them, which are behind the board and you
> cannot see.

Ah, I see what you're talking about and I've circled them in this photo:
http://www3.picturepush.com/photo/a/12511526/img/12511526.jpg

Like a good detective, you've seen something that I had not seen.
What you said makes sense. However, I have never heard of anyone
removing two transistors from that board. I wonder if those two
sets of inline pins are just the connections to the heat sink?

Since I have an FSU in my possession, I will try to lift the board.
The FSU that I have, DOES have two sets of these "spikes" sticking up
at those very locations, so, clearly "something" is there.
http://www2.picturepush.com/photo/a/12511535/img/12511535.jpg

But, what puzzles me is that nobody has ever mentioned removing
transistors from those two spots. Therefore, I suspect they're just
anchor posts, since the solder is clearly removed in the autopsies.

[Bimmer Owner]

On Mon, 25 Mar 2013 18:12:53 -0400, tm wrote:

> Yes, what Scott said. Where are the two transistors that were soldered in
> the pair of three holes on the right of the right photo.

I always thought those were just "posts" tying the circuit board
to something inside the FSU - but I do agree that all the FSU
autopsies show those posts being unsoldered to remove the board.

Here's the quote that came with this picture, for example:
http://www4.picturepush.com/photo/a/12511542/img/12511542.jpg

[QUOTE=sudnut]Ok, here are a couple of pics of my FSR from a 2002 E46
which is identical to FSR's in many other models and series of BMW.
The first is what you see when you scrape off the epoxy-like filling
covering the PCB. Using a hairdryer or better still a heatshrink gun
carefully without overheating. If you smell burning its too hot.
You should get a faint hot plastic odour that's all. I used one of
those cheap sets of precision flat screwdrivers, they can be sharp
so again be careful. You can see I gouged and scratched the circuit
board a little in places, just make sure you don't slice through any
tracks or lever off any components.
The second picture is a zoom of the 2 groups of 3 pins which I
believe are the cause of my FSR going crazy. If you look closely,
all six pins have cracks in the solder around the pins, most noticeable
are pins 1, 4 and 5 from left to right. My repair was simply to remelt
and resolder these pins with a little more solder using a hot and fine
tipped soldering iron, until I felt that the lead had flowed through
the board and hopefully to the other side where the components/resistors
are. If this repair doesn't last, I may remove the board fully and have
a better look on the other side.[/QUOTE]

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kir7q6$hpn$2...@news.albasani.net...

No, they are two TO-220 cased transistors. they are most likely attached to
the heat sink somehow. Like was mentioned before, finding out the part
numbers on those transistors will reveal a lot.

tm

[Bimmer Owner]

On Tue, 26 Mar 2013 04:22:30 +0000, Bimmer Owner wrote:

> But, what puzzles me is that nobody has ever mentioned removing
> transistors from those two spots. Therefore, I suspect they're just
> anchor posts, since the solder is clearly removed in the autopsies.

There is something critical about those two sets of inline posts
because, as I dig deeper, I see others concentrated on them also.

For example, the quote below came with the picture below:
http://www1.picturepush.com/photo/a/12511554/img/12511554.jpg

[QUOTE=olivier577]After soldering the lost/refound component,
remaking the joints of the 2 mosfet and testing the FSU alone
with an oscilloscope, here are my observations:
- the FSU works again
- there is no PWM , the gates signals are continuous voltage only ,
this is the reason why it heat so much its aluminium box...
In fact there is no point on the board where square signals are present.
Can somebody check its own FSU if it's the same ?
- the 2 bridges are in fact 2 resistors 10 milliohm used to balance
the currents between the 2 MOSFET and balance the power also.
The mesure of the DC voltage on those resistors can be used to
evaluate the current of the blower and its worn state.
- I guess the principal duty of the computer on the other side is
switching off the power transistors if the control voltage goes under 1V.
I put the FSU back in the car and it still work, I don't know if it will
last long. because of the heat...
Olivier[/QUOTE]

[Bimmer Owner]

On Tue, 26 Mar 2013 04:22:30 +0000, Bimmer Owner wrote:

> Ah, I see what you're talking about and I've circled them in this photo:
> http://www3.picturepush.com/photo/a/12511526/img/12511526.jpg

Looking more deeply, I find ANOTHER reference to the two MOSFETS,
which, are clearly the two transistors shown in the wiring diagram
that you had surmised must exist (by detective work).

Here's another quote which went along with this photo below
that mentions the unknown-as-yet MOSFETS:
http://www3.picturepush.com/photo/a/12511566/img/12511566.jpg

[QUOTE=olivier577]
The 2 MOSFET drain and source are tied together but the gates are differents

On the picture , one of the component is gone with the rubber foam : its
look like transistor : black with 3 pins ( it 's not bipolar transistors ).

It happen to me also : the component gone so easily that I didn't realize it,
maybe it is the issue for that FSU.

It is only while I compare to other pictures in the forum that there was
a lack of component on my board.

fortunately I found it together with the rubber foam parts, so I will
solder it back later[/QUOTE]

[Bimmer Owner]

On Tue, 26 Mar 2013 00:39:23 -0400, tm wrote:

> they are two TO-220 cased transistors.

> finding out the part numbers on those transistors will reveal a lot.

I have an FSU in my possession, so I will dig them out & snap
a photo when done and post back the results.

To my knowledge, nobody has ever posted a photo of what those
two MOSFETS look like, nor the part number.

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kir99g$hpn$5...@news.albasani.net...

As a general rule, MOSFETs are not used for linear current control. It is
more looking like this is a switcher (PWM) though I dont see an inductor.
Could be they just use the motor for that.

If you can see any numbers on the devices, it will help. Also, the solder
sure looks like RoHS shit tin.

[Scott Dorsey]

tra...@optonline.net <tra...@optonline.net> wrote:
>
>Maybe it's time to look at this thing like gas and brakes...
>You put gas in, you go so far. You put one of these
>blower modules in and you go for a few years again.
>It's not like they are a $500 or $1000 puter. Don't they
>cost like $50? I mean how much is time worth trying
>to reverse engineer it.....

This is how people are. At some point intellectual curiosity takes over.

In this case it might actually be worth it, because of the sheer number of
the things out there that are failing.... one person figuring the failure
mode out might save a lot of people that grief.

But mostly it's just intellectual curiosity.

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>On Mon, 25 Mar 2013 14:55:02 -0400, Scott Dorsey wrote:
>
>> Okay, notice on the lefthand photo, there are two sets of three solder joints
>> on the lefthand side of the board, which show signs of recent rework. There
>> are TO-220 transistors attached to them, which are behind the board and you
>> cannot see.
>
>Ah, I see what you're talking about and I've circled them in this photo:
> http://www3.picturepush.com/photo/a/12511526/img/12511526.jpg
>
>Like a good detective, you've seen something that I had not seen.
>What you said makes sense. However, I have never heard of anyone
>removing two transistors from that board. I wonder if those two
>sets of inline pins are just the connections to the heat sink?

No, there are two transistors bolted to the heat sink. That's why the heat
sink is there, to cool those two power transistors.

>But, what puzzles me is that nobody has ever mentioned removing
>transistors from those two spots. Therefore, I suspect they're just
>anchor posts, since the solder is clearly removed in the autopsies.

No, the spacing is consistent with a TO-220 transistor pair, and if it's
a linear pass regulator like it appears to be, there needs to be a big
transistor somewhere. Also, of course, there is the heatsink.

That IC is only control logic, it just takes some mystery input signal and
produces a variable voltage for the transistor base. Those two transistors
are doing all the hard work. BUT, if you want to replace the device with
a retrofit one, you need to know what that mysterious input signal is.

[Scott Dorsey]

tm <No_on...@white-house.gov> wrote:
>>
>
>As a general rule, MOSFETs are not used for linear current control. It is
>more looking like this is a switcher (PWM) though I dont see an inductor.
>Could be they just use the motor for that.

It's not a switcher. And those transistors may not be MOSFETs. But there
is no reason not to use mosfets in linear mode, other than the fact that
no two off the line have the same gain or transconductance.

>If you can see any numbers on the devices, it will help. Also, the solder
>sure looks like RoHS shit tin.

Agreed.

[tra...@optonline.net]

On Mar 26, 9:10 am, klu...@panix.com (Scott Dorsey) wrote:

One key question in all this is if the interface from car to
"resistor block" is some kind of simple digital interface,
ie it sends some bits that get interpreted as "go to speed 3"
or does it send a PWM signal. My guess is the latter.
That's my understanding of what BMW does with the aux
radiator fan in the X5. Another German electronic miracle
that fails and in doing so, mysteriously drains the battery.

Someone should put an oscilloscope on this and find
out what the signal looks like. If it sends a digital code,
then making a replacement from scratch is a big
hurdle. If it's sending a PWM signal, they you could
build an equivalent from Radio Shack parts. It still
seems like more work than it's worth.

How fast are these things failing for those that want
to make their own? 2002 X5 here and it's only had this
problem once, about 2 years ago and replacement one
is still working. And another data point. The failure on
that X5 resulted in the blower draining the battery when
the car was off. Blower ran fine. Only odd thing in
retrospect was that when the car was off, a couple times
I heard a faint noise. In retrospect, it was probably
the blower getting just enough current to start to turn
then stop. And only noticed it a couple times. The
bad thing with the failure mode of this and the AC fan
is that both were draining the battery and both were
very hard to pinpoint, resulting in huge labor charges.

[Bimmer Owner]

On Tue, 26 Mar 2013 09:10:56 -0400, Scott Dorsey wrote:

> BUT, if you want to replace the device with a retrofit one, you need to
> know what that mysterious input signal is.

All I know of the HVAC input signal is that it's a 2.0 to 7.8 VDC
signal from the HVAC controller, presumably to correspond to the
various levels of the fan blower motor speed.

[Bimmer Owner]

On Tue, 26 Mar 2013 07:37:09 -0700, tra...@optonline.net wrote:

> One key question in all this is if the interface from car to "resistor
> block" is some kind of simple digital interface, ie it sends some bits
> that get interpreted as "go to speed 3" or does it send a PWM signal.

All I know is that the HVAC controller sends a 2.0 VDC to 7.8 VDC signal
to one of the five pins of the FSU. I presume that directly corresponds
to the desired blower motor speed - but that is conjecture on my part.

> How fast are these things failing for those that want to make their own?

The originals fail within about 5 years. I've had my second one fail in
3 years. I think we can safely say about 3 to 5 years is the lifecycle
but nobody really knows for sure (least of all me).

> The failure on that X5 resulted in the blower draining the battery
> when the car was off. Blower ran fine. Only odd thing in retrospect
> was that when the car was off, a couple times I heard a faint noise.

This is one of the classic failure indications! Very very very common!
However, another classic failure indication, other than the dead
battery in the morning, is a blower that has a "mind of its own".

Together, those two sets of symptoms account for 99% of the failures.

Of all the anecdotal evidence presented, I don't think I've ever heard
of a failure being that the system was totally dead.

What that tells us, I don't know.

[Bimmer Owner]

On Tue, 26 Mar 2013 08:56:22 -0400, Scott Dorsey wrote:

> one person figuring the failure mode out might save a
> lot of people that grief.
>
> But mostly it's just intellectual curiosity.

Exactly!

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kisev1$ott$2...@news.albasani.net...

But is that a clean DC level or a pulse width modulated signal? If it was
measured with a multimeter, you won't know.

Has anyone probed around the module with a scope? Is that possible?

That and the question about the TO-220 devices. I think it would be possible
to make a better replacement if those questions were answered.

tm

[Francis C.]

tra...@optonline.net wrote:

> One key question in all this is if the interface from car to "resistor
> block" is some kind of simple digital interface, ie it sends some bits
> that get interpreted as "go to speed 3"
> or does it send a PWM signal.

Your idea about testing it is correct, however a bad one can work fine
until it gets hot enough for the IC chip to fail. Hvac control voltage is
0-8 VDC.

The load resistor should have a metal case mounted on a heatsink to
dissipate the heat if you are going to run the test more than a few
minutes.

My original 13 spike FSU was replaced twice under warranty, so the car
had 3 FSU's. When the 3rd old style failed i replaced it with the new
design FSU. That was 8-9 years ago, it is still working. One thing not
considered in your post is how many did not use OEM units, the $75 eBay
ones are junk. The $175 units at the stealer seem to hold up a little
better.

[Francis C.]

Scott Dorsey wrote:

> tra...@optonline.net <tra...@optonline.net> wrote:
>>It's not like they are a $500 or $1000 puter. Don't they cost like $50?
>> I mean how much is time worth trying to reverse engineer it.....

Bear in mind that the $75 Sitronic Ebay FSU is known to be even
more faulty than the $175 Valeo FSU from the stealer.

I can think of nice test equipment to buy instead of a $175 FSU every
few years!

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message

news:kisfan$ott$4...@news.albasani.net...

I don't even own a BMW. After this thread, I don't think I ever will.

[Bimmer Owner]

On Tue, 26 Mar 2013 15:30:41 +0000, Bimmer Owner wrote:

> All I know of the HVAC input signal is that it's a 2.0 to 7.8 VDC signal
> from the HVAC controller, presumably to correspond to the various levels
> of the fan blower motor speed.

Here is a picture of the BMW E39 HVAC/IHKA controller and sampling fan.
http://www4.picturepush.com/photo/a/12514687/img/12514687.jpg

I'm googling for specs as we speak.