OT Kinda MB Sprinter Glow Plug diagnosis

Mr Sandman

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Sep 17, 2013, 7:23:32 AM9/17/13

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Hi chaps,

my early Mercedes benz sprinter 308d had the glow plug light staying on,
which means a glow plug problem. So i have fitted new ones and now the
light doesn't come on at all. Anyone out there in diy world help me out
here with some advice? I have had the timer relay off and opened it up and
all looks fine in there. I am suspecting there must be more glow plug
controls somewhere? Does and one have a copy of the wiring diagram?

Cheers chaps

steve

Tim+

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Sep 17, 2013, 7:47:35 AM9/17/13

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Mr Sandman wrote:
> Hi chaps,
>
> my early Mercedes benz sprinter 308d had the glow plug light staying
> on, which means a glow plug problem. So i have fitted new ones and
> now the light doesn't come on at all.

Did it need new ones?

You're best arming yourself with a cheap multimeter and then you can check
to see if any have gone open circuit or whether they are getting power in
the first place. Replacing things before making a diagnosis can get
expensive!

Anyone out there in diy world
> help me out here with some advice? I have had the timer relay off
> and opened it up and all looks fine in there.

Is it producing a 12V output for an appropriate period? Telling us it
"looks fine" isn't a great deal of help.

> I am suspecting there
> must be more glow plug controls somewhere? Does and one have a copy
> of the wiring diagram?

Nope, but I've crossposted this to uk.rec.cars.maintenace where you'll stand
a better chance of getting a reply from someone much better informed than
me! ;-)

Tim

Baz

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Sep 17, 2013, 11:00:07 AM9/17/13

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"Tim+" <timdow...@obvious.yahoo.co.uk> wrote in message
news:5238414f$0$1169$5b6a...@news.zen.co.uk...

The Only problem I have had with GlowPlugs, was the Fuse had blown.

Baz

Mrcheerful

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Sep 17, 2013, 5:56:58 PM9/17/13

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does it start ok? did the glow plug light come on before (in the same
temps)?

I had a fusion in the other day with engine light coming on sporadically
and going into limp home mode for a short time, code reading said glow
plugs/circuit, every glow plug tested ok and glowed nicely when tested
out of the engine, yet replacing all four has got rid of the problems.
modern ecu checks the glowplugs every few minutes and if the figures
differ from the presets by even a tiny amount the lights come on.

Mr Sandman

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Sep 18, 2013, 5:14:04 AM9/18/13

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"Tim+" wrote in message news:5238414f$0$1169$5b6a...@news.zen.co.uk...

Mr Sandman wrote:
> Hi chaps,
>
> my early Mercedes benz sprinter 308d had the glow plug light staying
> on, which means a glow plug problem. So i have fitted new ones and
> now the light doesn't come on at all.

Did it need new ones?

You're best arming yourself with a cheap multimeter and then you can check
to see if any have gone open circuit or whether they are getting power in
the first place. Replacing things before making a diagnosis can get
expensive!

Yes it did need new ones, two of them were reading very high resitance. So
i replace them all as a set.

Anyone out there in diy world
> help me out here with some advice? I have had the timer relay off
> and opened it up and all looks fine in there.

Is it producing a 12V output for an appropriate period? Telling us it
"looks fine" isn't a great deal of help.

No, there is no output from the relay, but there is a 12v supply to the
large terminal. By 'looks fine' i mean there are no obvious signs of
shorting, corrosion or dry joints etc inside it.

> I am suspecting there
> must be more glow plug controls somewhere? Does and one have a copy
> of the wiring diagram?

Nope, but I've crossposted this to uk.rec.cars.maintenace where you'll stand
a better chance of getting a reply from someone much better informed than
me! ;-)

Thanks for that.

Tim

Steve

Mr Sandman

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Sep 18, 2013, 5:14:44 AM9/18/13

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"Baz" wrote in message news:RtmdndCFjIDE86XP...@bt.com...

I checked the fuses under the steering wheel, none are blown.

Ta

steve

Mr Sandman

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Sep 18, 2013, 5:16:36 AM9/18/13

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"Mrcheerful" wrote in message news:qe4_t.107389$Iu6....@fx31.am4...

No, it wont start. The problem first showed itself as a glow plug light
that wouldn't go off once started..it stayed on all the time. Then it got
harder to start and finally the glow light didn't light at all. So i
replaced the glow plugs and there is still no light on the dash.

Ta

Steve

Mr Sandman

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Sep 18, 2013, 5:17:22 AM9/18/13

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"Tim+" wrote in message news:5238414f$0$1169$5b6a...@news.zen.co.uk...

Mr Sandman wrote:
> Hi chaps,
>
> my early Mercedes benz sprinter 308d had the glow plug light staying
> on, which means a glow plug problem. So i have fitted new ones and
> now the light doesn't come on at all.

Did it need new ones?

You're best arming yourself with a cheap multimeter and then you can check
to see if any have gone open circuit or whether they are getting power in
the first place. Replacing things before making a diagnosis can get
expensive!

Yes it did need new ones, two of them were reading very high resitance. So
i replace them all as a set.

Anyone out there in diy world
> help me out here with some advice? I have had the timer relay off
> and opened it up and all looks fine in there.

Is it producing a 12V output for an appropriate period? Telling us it
"looks fine" isn't a great deal of help.

No, there is no output from the relay, but there is a 12v supply to the
large terminal. By 'looks fine' i mean there are no obvious signs of
shorting, corrosion or dry joints etc inside it.

> I am suspecting there
> must be more glow plug controls somewhere? Does and one have a copy
> of the wiring diagram?

Nope, but I've crossposted this to uk.rec.cars.maintenace where you'll stand
a better chance of getting a reply from someone much better informed than
me! ;-)

Mrcheerful

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Sep 18, 2013, 7:34:17 AM9/18/13

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I assume that the relay does not click when you first turn on the ign?
if no, then it is not getting its signal to go, or the relay is faulty
OR the coolant temp sender is telling it not to go because it thinks it
is already warm.

If it does click in, then either the feed to it is faulty or the output
does not reach the plugs.

Mrcheerful

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Sep 18, 2013, 8:04:19 AM9/18/13

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Is it possible that you disturbed the coolant sensor when changing the
plugs?

Mr Sandman

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Sep 18, 2013, 8:13:23 AM9/18/13

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"Mrcheerful" wrote in message news:8Fg_t.107574$6P7....@fx26.am4...

Where is the coolant sensor.....:-) lol

I am not getting any click from the relay. I seem to remember that even in
hot weather the glow plug light would come on as it does in the winter.

Ta

Steve

Mrcheerful

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Sep 18, 2013, 9:17:50 AM9/18/13

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what year and what engine size is this 308d? I may be able to look at
the wiring diagram and get a better idea. no idea where the coolant
sensor for the glow plugs lives, sorry. I will try and work out which
legs of the relay are which once I know which one to look at.

The Natural Philosopher

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Sep 18, 2013, 9:27:58 AM9/18/13

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On 18/09/13 10:16, Mr Sandman wrote:
>
> No, it wont start. The problem first showed itself as a glow plug
> light that wouldn't go off once started..it stayed on all the time.
> Then it got harder to start and finally the glow light didn't light at
> all. So i replaced the glow plugs and there is still no light on the
> dash.
>

mm. unless its very cold, the glow light doesn't come on on the dash
here either.
But it does start.

possibly whatever it is that detects when its cold enough to need the
glo plugs has failed.

> Ta
>
> Steve

--
Ineptocracy

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Mr Sandman

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Sep 18, 2013, 9:49:04 AM9/18/13

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"Mrcheerful" wrote in message news:WJh_t.68896$H%2.1...@fx16.am4...

I did some more multimetering, and discovered there is a switched 12v supply
to the black box/relay/preheat timer delay jobbie as well as the permanently
live one. I found a wiring diagram (in Dutch but heho) on the net in some
deep recess, and it is looking like the temperature may be at fault, if not
that then its gotta be the above black box thingy. Does anyone know what
these sensors are supposed to read resistance wise? i maybe able to find a
resistor to emulate a cold engine...

Cheers

Steve

Mr Sandman

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Sep 18, 2013, 9:49:55 AM9/18/13

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"Mrcheerful" wrote in message news:WJh_t.68896$H%2.1...@fx16.am4...

Oh yeah, its a 308d 1998 i think its a 2.3 non turbo.

Cheers

steve

Mr Sandman

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Sep 18, 2013, 10:01:05 AM9/18/13

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Update. Checked the temperature sensor, it is reading 4.5Kohms and 13C
here.....

Steve

The Natural Philosopher

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Sep 18, 2013, 10:39:27 AM9/18/13

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the general temp range on the (dead) sensor I pulled out of pegeot GTI
from the ECU was supposed to be about 3k room and 300 ohm boiling low
iompedance works best on cars,,,

> Cheers

The Natural Philosopher

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Sep 18, 2013, 10:41:23 AM9/18/13

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that sounds spot on, and if its high, it would make the thing operate,
rather than t'other way around.

I wonder if you blew a fuse when fiddling?

Dave Liquorice

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Sep 20, 2013, 6:10:03 PM9/20/13

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On Wed, 18 Sep 2013 10:14:44 +0100, Mr Sandman wrote:

> I checked the fuses under the steering wheel, none are blown.

And you found fuses for glo-plugs in there? Glo-lugs take quite a
hefty current, I'd half expect the fuse(s) for them to be in an
engine compartment fuse/relay box.

--
Cheers
Dave.