[GMCnet] Alternator issues 1976 Palm Beach

[Samuel Ferguson via Gmclist]

I am experiencing a charging issue with the engine battery on a 1976 GMC Palm Beach Motorhome. I had the engine battery to go dead while going down
the highway. I took the alternator off and took it to NAPA parts store for a bench test and was told the alternator was "dead"! I replaced with a
remanufacture alternator. After doing so, I started the engine and the "GEN" light came on. I turned the ignition off and waited a couple of minutes
an re-started the engine.  After re-starting, the "GEN" went off, but it still did not appear to be charging. I checked the battery and am showing 12
volts. I checked the "red" wire to the alternator prior to starting the engine again and I do not have any power. I started the engine and am still
not getting and voltage reading on the red wire to the alternator.

The "yellow" wire coming from the alternator plug is showing 12 volts when I check it against the brown wire next to the yellow wire in the plug.

I have traced the red, yellow, and brown to the from of the hood area looking for an in-line fuse link or a voltage regulator box (Nothing found). All
three wires run to the hood area and after doing so, the red wire is piggy-backed with another red wire running to a blue box {mounted on the back
wall with GMC 706751 labeled) with one red wire going to a solenoid. The yellow wire coming from alternator runs to the hood area and is pig-tailed
with a red wire, which the red wire goes to one of the three post on top of the blue GMC 706751 box.
I did discover today, when I turn the house battery on, the red wire on the alternator is reading 12 volts. Turn house battery off and turn engine
battery on, no voltage reading on the red wire at alternator.

I am trying to find out of the blue GMC box is the problem or would it be a bad solenoid? I have attached a couple of pictures of the blue box and the
solenoid.

Any assistance will be greatly appreciated.

Samuel Ferguson 

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[Johnny Bridges via Gmclist]

If a wire shows voltage with the house battery on but not when it's off, that wire is connected in some manner to the house battery. Your description
sounds as if the PO or Os have been playing with the wiring. Have a look at the PROPER schematic for your coach - it's in the back of the maintenance
manual - take your meter, and prove all the 12 volt connections to the isolator and underhood components. There's likely a miswire in there
somewhere.

--johnny

--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

[Samuel Ferguson via Gmclist]

I did find a cable that runs from engine battery compatment to the back of rv (I assume this cable is the battert boost cable) has a lot of coating
worn from it which is possibly shorting out. I unhooked and ordered another alternator. Hoping this is my problem that caused new alternator to burn
up!

[Samuel Ferguson via Gmclist]

Replacing alternator again tomorrow. Does anyone have a schematic for the wiring from alternatir and which post the wire goes to on the battery
isolator? Isolator has 3 posts GMC #706751.

Thank You

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[Bruce Hislop via Gmclist]

Go here and you can download the wiring diagram for your coach.

The ground for the alternator is the case of the alternator itself, all voltage measurements are made from the case of the alternator.

The brown wire is the startup excitation wire. It has a resistance in the wire and provides the field current to get the alternator going. The voltage
on this wire when the engine is NOT Running but the key is ON is something less than battery voltage. I've never had a cause to measure it myself, but
I'm guessing maybe 1/2 battery voltage (6 volts).

The wire beside it in the connector (white or red) is the battery voltage sense wire. This wire should have battery voltage on it. It senses the
battery voltage to give the voltage regulator a feedback voltage of what the battery voltage currently is.

The output wire is a larger wire on a bolt stud. When the engine is RUNNING, it should be 0.7 volts higher than the battery voltage. When the engine
is OFF, this wire should be near Zero volts.

hope this helps,


--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

[Ken Henderson via Gmclist]

Samuel,

Bruce missed answering just one of your questions: The output of the
alternator should be connected to the center terminal of the isolator. The
batteries are each connected to one of the other terminals.

Ken H.

[Samuel Ferguson via Gmclist]

Thank You

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[Mike Kelley via Gmclist]

Sam F:
How long have you owned your GMC?
I am surprised we have never seen you at a GMC 6 Wheeler function (within a 200 mile range of Chicago).
We have a rally next week in Pontiac, IL.
Mike/The Corvair a holic
Peoria, IL.
76 GMC Eleganza II 26’ (our best and soon to be for sale).
76 GMC Glenbrook 28’ stretch
78 GMC Glenbrook - project coach

Sent from my iPhone

[Samuel Ferguson via Gmclist]

Just bought it 2 weeks ago. It's been sitting 20 plus years in a barn. Going through, trying to get all the bugs out!!!! Looking forwad to going to
the get togethers in the future...

Sam

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[Mike Kelley via Gmclist]

Sam:
Ahah - a Newbie.
Also sounds like you have mechanical skills - good for you.
The GMC 6 Wheelers is your local GMC club.
We meet (usually the 3rd weekend) of ea month May thru Oct. The Sept. rally will be 9/19 thru 9/22 (Thur. thru Sun. AM) at the Pontiac, IL. 4H facility. Our Oct. rally will be at Geneseo, IL. 10/17 thru 10/20 (Thur. thru Sun. AM).
As a GMC owner you are invited whether you bring your GMC or not and whether you stay a few hours or all weekend!
It’s a good group and we look forward to meeting you.
Visit our website at GMC6wheelers.org at your convenience. Yearly cost to belong is just $10.00 - the best bargain in town.
Mike/The Corvair a holic

Sent from my iPhone

[John R. Lebetski via Gmclist]

The isolator is 2 diodes one each going from the center to an outer terminal. That's why you can't read voltage engine off at the alternator terminal
because you can't see the battery in that direction like wpuld br on a passenger car. I would start by metering the diodes. I would disconnect both
battery negative cablofirst not knowing PO wiring mods. The sense wire is after the diode on the engine battery side.
--
John Lebetski
Woodstock, IL
77 Eleganza II

[Samuel Ferguson via Gmclist]

Put new alternator on this afternoon. My meter is reading 36.9 when engine is running on the alternator wire..(Hoping this is a correct reading!!!).
Battery is at 12.4 volts, while I have'nt checked reading on alternator while not running.
Isolator box - I have 12 4 volts to engine battery. 11.2 volts to house battery. Alternator post on isolator reading the 36.9. (Hope this is correct)

Dash AC working fine enough to figure out I need to recharge the freon. Switch on "hi" and she blows somewhat cool air, but not cold air.

Next project - trace the Booster Batter Cable and replace. Cable has the coatin falling off from touch, and several section of exposed wire, which is
obviously grounding somewhere and possibly "fried" the last two alternators. (Fingers crossed this was the problem)
Once cable traced, I plan to run a brand new one from engine compartment to house battery...

I would like to say "Thank You" to all that responded and gave me tips of what to check, look for, and provided a step by step plan to accomplish what
I had got myself into. I am a newbie to this sort of thing. I grew up learning how to do electrical and mechanical troubleshoots and repairs, but as I
age as others do, I am slow to retrieve what information I took in 30 - 40 years ago. And when I do get the problem figured out, I start trying to
patch the hair I have pulled out of the side of my head and try to place it back to the bald spots I gave myself in the last 6 to 10 hours.
All is starting to look good. A few more bugs to work out and hopefully my wife and I can make a roadtrip in the Palm Beach to one of the two meetings
this year before winter makes it way..

Again, Thank You all for your kindness, support and expertise...

Samuel Ferguson

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[Stu Rasmussen (97381.com) via Gmclist]

36.9 volts on the center post of the isolator (and alternator output) is
wrong wrong wrong.

This sounds like both diodes in the isolator are completely open.

Alternator voltage with good diodes should be approximately 0.7 volts
higher than battery voltage; or about 13 volts DC positive with respect
to chassis ground.

Stu

On 9/13/2019 5:33 PM, Samuel Ferguson via Gmclist wrote:
> Put new alternator on this afternoon. My meter is reading 36.9 when engine is running on the alternator wire..(Hoping this is a correct reading!!!).
> Battery is at 12.4 volts, while I have'nt checked reading on alternator while not running.
> Isolator box - I have 12 4 volts to engine battery. 11.2 volts to house battery. Alternator post on isolator reading the 36.9. (Hope this is correct)
>

[Stu Rasmussen (97381.com) via Gmclist]

36.9 volts on the center post of the isolator (and alternator output) is
wrong wrong wrong.

This sounds like both diodes in the isolator are completely open.

Alternator voltage with good diodes should be approximately 0.7 volts
higher than battery voltage; or about 13 volts DC positive with respect
to chassis ground.

Stu

On 9/13/2019 5:33 PM, Samuel Ferguson via Gmclist wrote:
> Put new alternator on this afternoon. My meter is reading 36.9 when engine is running on the alternator wire..(Hoping this is a correct reading!!!).
> Battery is at 12.4 volts, while I have'nt checked reading on alternator while not running.
> Isolator box - I have 12 4 volts to engine battery. 11.2 volts to house battery. Alternator post on isolator reading the 36.9. (Hope this is correct)
>

[Samuel Ferguson via Gmclist]

Stu,

Would you have any info as to where I could order a new isolator? Part # on mine is GMC #706751.

Sam

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[Bruce Hart via Gmclist]

Sam
Napa has them

https://www.napaonline.com/en/p/BK_7821769?partTypeName=Battery+Isolator&keywordInput=battery+isolator

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class

[Charles Boyd via Gmclist]

Got mine at O'Reillys. Didn't use the 4th little connector.
https://www.oreillyauto.com/detail/b/super-start-4986/battery-accessories-16452/battery-isolators-17648/8cb8993005ef/super-start-95-amp-battery-isolator/08770/4742278?q=Battery+isolator&pos=1



--
C. Boyd
76 Crestmont
East Tennessee

[Larry Davick via Gmclist]

And Jim K. <https://www.gmcrvparts.com/product-p/gm7-070.1a.htm>

Larry Davick

[Stu Rasmussen via Gmclist]

OK Samuel, you now have three options for a replacement isolator.

You said earlier "Next project - trace the Booster Batter Cable and replace. Cable has the coatin falling off from touch, and several section of

exposed wire, which is obviously grounding somewhere and possibly "fried" the last two alternators. (Fingers crossed this was the problem)"

That may indicate the genesis of your alternator and isolator failures.

As a temporary expedient (and to prevent further damage) you can completely eliminate the isolator and connect the alternator lead to the starting
battery and leave the house batteries completely disconnected while you troubleshoot the house battery issue. Having insulation flaking off the heavy
wire may indicate it shorted and burned up rather a lot of 'stuff' and replacing the isolator might just start the destruction all over again.

Disconnect both the house and paralled 'booster' battery until the wiring is repaired.

JMHO

Stu

Stu
--
Stu Rasmussen W7QJ
Silverton, OR
gutted '74 Eleganza II (for sale now)
'77 Birchaven

[Ken Burton via Gmclist]

Last time I needed one they were around #30.00 for a 95 amp one at a local auto parts store. I forget which one I got it from. The local AutoValue
store has them hanging on one of the boards. I probably got it from AZ or Oreilies. Also any RV store or Jim K. will have them.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Samuel Ferguson via Gmclist]

Will do.

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[Larry Davick via Gmclist]

While you are at it - Mr. ERF has some fantastic tips on his photo site folder <http://www.gmcmhphotos.com/photos/g5493-gmc-cranking-improve-for-free.html <http://www.gmcmhphotos.com/photos/g5493-gmc-cranking-improve-for-free.html>>

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, CA
Howell EFI + EBL + Electronic Distributor

[Samuel Ferguson via Gmclist]

I did find last night in the fuse panel (glove box), the "Aux. Battery" fuse keeps blowing. I am thinking, I obviously have a short! Could it be from
house battery to front or is it possible the isolator box or solenoid is bad?

Samuel

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach

[James Hupy via Gmclist]

What part of "deteriorated insulation on a large unfused conductor" does
not cause you cause for concern. Disconnect ALL BATTERIES NOW and replace
that wire before it burns your coach to the lugnuts.
Don't buy any more alternators until you fix this. Please heed my warning
on this. We aren't making any more GMCs.
Jim Hupy
Salem, Oregon

[Samuel Ferguson via Gmclist]

Batteries are not hooked up. As soon as I found the bare wires, overcharging, fuse blowing issues, I unhooked them. I am checking everything with a
meter at this point looking for anything and everything that needs replaced.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)

1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Charles Boyd via Gmclist]

Sir, if you are replacing the big wire from boost solenoid to generator compartment there is a connector behind the wall in the fuse box cabinet .
You might be able to see it with a good light and a mirror. The connection is an isolated insulated stud fastened to the wall frame. There should be
a good size wire going to it from the 12 volt fuse block. The big wire goes to it then another same wire goes from there to generator compartment.
It is not a one piece wire from front to back. I have never replaced this wire but possibly you could unbolt from stud and hook new wire and pull
thru? I don't know if there are clamps or hangers in between?

--
C. Boyd
76 Crestmont
East Tennessee

[Charles Boyd via Gmclist]

I have heard rumors of others fishing a small size water hose over existing wire to insulate it. I have no evidence of this working or not.




C Boyd wrote on Sat, 14 September 2019 11:47

[Ken Burton via Gmclist]

Am easier quick fix is to use Split Loom tubing. Replacing it is a better long term solution.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Ken Henderson via Gmclist]

Steve,

In no way minimizing the importance of everyone's comments about getting
those wires insulated, but I've seen no reply to your question about the
Aux. Battery fuse. First off, do you have the wiring diagram for your '76
Palm Beach? If not, you need to go to bdub.net or another source and get
it NOW. You might also find it useful, especially in view of the state of
your electrical system, to acquire one of the large copies of the wiring
diagram produced by my son (www.bdub.net/GMC_Motorhome_Wiring_Diagrams.pdf)
(discounted copies of which will be available at GMCMI Mansfield).

More directly to the fuse question: That fuse supplies the solenoid boost
relay on the passenger side firewall. It also feeds the similar relay
located in the rear battery compartment (it bypasses the aux. battery
circuit breaker during boost selection). You should check those relays for
internal and external shorts as the easiest starting point. If you don't
find the problem there, the much more laborious task of finding the shorted
wire becomes necessary. I'd start by disconnecting the relay ends of the
wires and metering the loosened wires with an Ohmmeter (with all battery
and shore power disconnected), following the wiring diagram to know just
what I was checking. It is very unlikely that the house battery or the
isolator is directly responsible for the fuse blowing.

HTH,

Ken H.

On Sat, Sep 14, 2019 at 10:41 AM Samuel Ferguson via Gmclist <
gmc...@list.gmcnet.org> wrote:

> I did find last night in the fuse panel (glove box), the "Aux. Battery"
> fuse keeps blowing. I am thinking, I obviously have a short! Could it be
> from
> house battery to front or is it possible the isolator box or solenoid is
> bad?
>
> Samuel
>

[Johnny Bridges via Gmclist]

Silly question - you HAVE proved the isolator has failed using a reliable ohmmeter, have you not? If you have not, do so before replacing it. The
isolater is a low failure item. Simply take the wire(s) off the upper and lower terminals and m,easure the center to each with your ohmmeter. Then
reverse the probes and measure again. You should see low resistance with the probes one way and high the other. This is done with an analog
ohmmeter, or with the diode test setting on adigital meter.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

[Samuel Ferguson via Gmclist]

In past posts, I assumed I had issues with an alternator after having to change out on alternator 3 times already, I have traced battery wires from
the front of the coach (engine battery) to the house battery. I have ordered solenoid to replace the solenoid on passenger side engine compartment. I
have ordered an isolator box from NAPA last Friday and it is over a week getting here, to which UPS claims the item possibly got lost or misplaced.
(Imagine that!!)
I am at a loss with the large cable with red coating on it, coming from the left side of the solenoid located on the passenger firewall, next to the
isolator box. The wire is strapped to the frame behind the grill and runs to the driver's side section and then goes into the body of the camper.
(From here, I have no clue) I thought I had found the other end of this cable at the block behind the Converter/Breaker box across from bathroom.

I did remove the Converter box and Breaker Box today and found a "block" that a battery cable wire connects to. With the house battery connected, this
wire has 11.5 -12 volts. I did unhook the wire which appears to be going back to the front of the camper, and while hooked to a battery, it is showing
12 volts. The wire on the block is "zero" I am unsure if the cable I am mentioning is in fact the booster cable...

I do have several decent pictures of the areas I am trying to explain. I must admit when I look at a schematic or any other electrical drawing, it
comes across to me a trying to read Chinese, which I have no clue of. I am more of a type of person, if I can get my hands on it and be able to look
at how it is to go, I can eventually figure it out.

I do apologize for my ignorance and to assure all, I jumped in this purchase of this RV to learn the aspects of how to keep it maintained and serviced
when needed. If and When I get the bugs worked out, it will be going on the road!!! Please forgive me for my ignorance with the above mention, but I
am convinced I will not let this eat my lunch or kick my butt.

I do have a few photos I have taken, but it seems when I try to upload them, I am advised they are too big to send. Another task I am sure I will
eventually figure out.

1976 Palm Beach
Samuel Ferguson
Tele 217-491-2969

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Ken Henderson via Gmclist]

Samuel,

First off, please quit "throwing parts at" your problem, like a modern,
ill-educated, mechanic. It's very doubtful that all the items you've
mentioned have failed simultaneously and you're just wasting time and money
replacing them without figuring out why. We'll help you learn to diagnose
the individual parts.

Second, learn to post photos. You need to find a program to compress those
from "too big" down to probably 800x600 pixels. There are numerous free
programs available. I use XNView, but the compression routine is a tiny
part of that program, which may not suit your needs. Google something like
"photo compression".

You've pretty much described a standard electrical system -- don't change
anything until you've posted photos to GMCMHPhotos and let us help your
diagnosis.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

[Samuel Ferguson via Gmclist]

I have started over and am beginning to weed out the alternator issue. ​
​
I have replaced the alternator twice. Prior to replacing the alternator this time, I checked wiring with a digital meter to find out of there were any
shorts. ​
​
So far, I have found the booster cable to have coating missing from it where the wore runs on top of the frame behind the grill area. I did check the
wire for any other grounding all the way back to the wiring block (located behind the converter/breaker box) house battery and found no other issues.
I covered the exposed booster cable section with a insulator covering.​
​
Other wiring and items checked (I think is related to the alternator) -

Isolator box - No battery hooked up - Checked the continuity -
"center" lug to "right" lug -I show a 839 reading,
"center lug to "left" lug - showing zero
"left" lug to "right" lug - showing zero

Wiring 1st picture attached:

a red wire from alternator is going to "center" lug. This wire also pigtails and goes to a wire connector connecting to a green wire with a fuse
link, and then goes to the back of the fuse panel box.

Right lug (isolator) - Wire goes to left side of solenoid

Left lug - going to post under "vehicle battery post" sticker.

Solenoid - 2nd picture attached - The way it is wired now.

Left large post - Booster cable, Right post isolator

Left small post - ground

Right small post - wires going towards wiring harness

Right large post - + battery, starter, jumper to "vehicle battery" post

My problem -- When I start the vehicle, I check the output of the alternator on red wire coming from back, and I get 36.9 volts. I am told I should
only see .7 volts.

Any suggestions ????

Samuel

[James Hupy via Gmclist]

Samuel, Stop, and take a deep breath. Clear you mind, and consider ONLY one
problem at a time.
Let's consider ONLY the alternator and isolator. The isolator is a
DEAD SIMPLE DEVICE. It works electrically in much the same way that a flow
check valve works in a plumbing system. IT ONLY ALLOWS ELECTRICITY TO FLOW
IN ONE DIRECTION.
There is a large conductor, it is supposed to be red in color, that
comes DIRECTLY FROM the output lug on the alternator and ONLY GOES to the
CENTER TAP on the isolator.
WITH THE ENGINE RUNNING, THE VOLTAGE THAT YOU READ ON THE OUTPUT LUG
of the alternator should be exactly the same amount as the voltage that you
read between the isolator CENTER TAP and a good ground point. If it does
not, something is bad in that circuit.
The other TWO LUGS, upper and lower, should read that voltage, MINUS
.7 volts. If either of them does not, REPLACE THE ISOLATOR. It is bad.
Then, you can start tracing the electron flow from there.
Jim Hupy
Salem, Oregon

[Samuel Ferguson via Gmclist]

Yes, I have the conductor from alternator - When engine running, I am showing 34. to 36.9 volts from alternator to center lug of isolator.

The same voltage showing to right side of isolator.

No reading showing on left side of isolator.

[James Hupy via Gmclist]

You either have your meter on the wrong scale, you have a faulty meter, OR,
your alternator is running away, ( no regulation) it should be in the range
of 14.5 volts. If it is not your meter setting, then your alternator is
bad. Fix that before you do anything else.
Jim Hupy
Salem, Oregon

[Samuel Ferguson via Gmclist]

James,

Can you give me an exact description of what replacement alternator I need. I have been dealing with NAOA here locally and this is the second
alternator I put on in 3 weeks. The 1st one ran about 2 minutes and appeared to be laboring hard and then nothing on output. Both are re-manufactured.
I have read the re-manufactured ones are like flipping a coin as to how long they will work. I think I will skip remanufactured if possible.

I do know NAPA was unable to search by looking up 1976 GMC Palm Beach. One if the guys in parts store mentioned the alternator was the same as fits a
Tornado engine!!! Is this true?

My question is: What info do I input if I were to order online and have shipped to my house. Or is there a parts distributor that you might recommend?

[Charles Boyd via Gmclist]

Sir make sure meter is on DC volts and using red lead to + and black lead to -. Now remove pigtails fuse to fuse box and leave only red wire to
battery isolater and see what you got.






Samuel Ferguson wrote on Sat, 21 September 2019 16:17
> James,
>
> Brand new digital meter. Meter was set on 20 volts, then I checked it with 200 volts.

>
> Can you give me an exact description of what replacement alternator I need. I have been dealing with NAOA here locally and this is the second
> alternator I put on in 3 weeks. The 1st one ran about 2 minutes and appeared to be laboring hard and then nothing on output. Both are
> re-manufactured. I have read the re-manufactured ones are like flipping a coin as to how long they will work. I think I will skip remanufactured if
> possible.
>
> I do know NAPA was unable to search by looking up 1976 GMC Palm Beach. One if the guys in parts store mentioned the alternator was the same as
> fits a Tornado engine!!! Is this true?
>
> My question is: What info do I input if I were to order online and have shipped to my house. Or is there a parts distributor that you might
> recommend?
>
> Samuel


--

C. Boyd
76 Crestmont
East Tennessee

[Matt Colie via Gmclist]

Samuel Ferguson wrote on Sat, 21 September 2019 16:17
> James,
>
> Brand new digital meter. Meter was set on 20 volts, then I checked it with 200 volts.
>

> Can you give me an exact description of what replacement alternator I need. I have been dealing with NAOA here locally and this is the second
> alternator I put on in 3 weeks. The 1st one ran about 2 minutes and appeared to be laboring hard and then nothing on output. Both are
> re-manufactured. I have read the re-manufactured ones are like flipping a coin as to how long they will work. I think I will skip remanufactured if
> possible.
>
> I do know NAPA was unable to search by looking up 1976 GMC Palm Beach. One if the guys in parts store mentioned the alternator was the same as
> fits a Tornado engine!!! Is this true?
>
> My question is: What info do I input if I were to order online and have shipped to my house. Or is there a parts distributor that you might
> recommend?
>
> Samuel

Samuel,

Always us a first default for ordering parts as a {1973, GMC, Transmode, 7.5l} if it is there. For an alternator, a 7(3~6) Toronado with A/C is a
pretty good next choice. (What I think is a great joke about the 73 transmode in most catalogs is that 73 was the year that there were no transmodes.


You cannot buy a real Delco 27SI new, not for years now. Getting a rebuild by a local shop is a better bet than any box job. The problem is that
those shops are a dying breed. I used to work with five different shops. I now have just one. The good guys in there are as old as I am.....

Our Alternators are somewhat special. They are supposed to be "Remote Sensing". This is essential because of the 0.7V drop caused by isolator.

From the post above by several, with the isolator open, the reference voltage back to the alternator is open. That will cause the machine
(alternator) to go to wide open. This can kill them if it is that way at higher than idle speeds.

I hate NAPA's online catalog, it sucks more than a California paper straw.

Matt


--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[Samuel Ferguson via Gmclist]

63 amp or 100 amp?

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Samuel Ferguson via Gmclist]

One side of isolator it read 34 - 36v same as center lug. Other side zero.

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Matt Colie via Gmclist]

Samuel Ferguson wrote on Sat, 21 September 2019 18:00

> 63 amp or 100 amp?

I have found that most of the available are the 100 Amp, Some were also 80.
Just get what you can that works.

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[James Hupy via Gmclist]

O.K. Samuel, let's go back one more step to very basic electricity.
Let's verify that you have your meter set correctly. You should be on
DC VOLTS. If your meter has a 20 volt scale, that should work. If
it doesn't, and has a 200 volt scale or is auto ranging, use that.
Place the meter lead that is marked "positive" ( should be the red
lead) on the positive battery post, and the lead marked "negative" (should
be black) on the battery negative post.
If your battery is good, and has a full charge, the meter should read
12.5 volts DC or better. But, no higher than 13.2 volts DC. If it does,
with the engine NOT RUNNING, something is wrong with your meter settings,
or the meter itself is not working right. So do that, and let us know that
we are singing off the same music.
Jim Hupy
Salem, Oregon

[Samuel Ferguson via Gmclist]

James,

Digital meter has 20v & 200v setting. Checked all on both settings and get the collosing:

Battery showing 12.5 volts with ignition off.

Engine running- alternator is showing 34 volts output on red wire coming from back of alternator to center post of isolator box.

Samuel

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[James Hupy via Gmclist]

Don't run it like that. Remove the alternator and have it tested. Check the
wire harness that you have on your coach, particularly on the part of the
harness that plugs into the alternator.
Jim Hupy

[Ken Henderson via Gmclist]

Jim & Steve,

It sounds to me like the alternator may be OK, but the isolator's got a bad
chassis battery diode, preventing the runaway alternator from getting
feedback voltage from the chassis battery. Being on email only, I can't
see any of the photos to help follow the narrative. At any rate, the
alternator, even without feedback on the sense line should be internally
limited to 18 VDC (but they aren't all!).

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

[Charles Boyd via Gmclist]

Sir, does your alternator have a small plug above the big red one with 2 small wires in it?







James Hupy wrote on Sat, 21 September 2019 20:20

--
C. Boyd
76 Crestmont
East Tennessee

[Samuel Ferguson via Gmclist]

Yes Sir. There is a plug with 2 wires. White and brown.

[Charles Boyd via Gmclist]

The wire closest to the big red wire is #1 the wire furthest away from big red wire is #2 and should have 12 volts on it with key on. Does it? What
is #1 voltage?

Ken we got no pics on Forum either.





Samuel Ferguson wrote on Sat, 21 September 2019 20:46

> Yes Sir. There is a plug with 2 wires. White and brown.
>
> Samuel


--

C. Boyd
76 Crestmont
East Tennessee

[Samuel Ferguson via Gmclist]

12 volts on #2 wire with key on. #1 wire had voltage on it so, but it had a lower voltage than #2 wire.

I cant figure out how to upload pics on here. I found a photo compressing program, but still trying to figure it out. Sorry

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Charles Boyd via Gmclist]

Well Col Ken and everybody else knows a lot more than I do about electrics and GMCs. But the book says you have an internal short in the alternator
and needs to be checked.

I haven't figured out how to resize the pics either. I'm using an IPad and it is different..





Samuel Ferguson wrote on Sat, 21 September 2019 21:26

> 12 volts on #2 wire with key on. #1 wire had voltage on it so, but it had a lower voltage than #2 wire.
>
> I cant figure out how to upload pics on here. I found a photo compressing program, but still trying to figure it out. Sorry
>
> Samuel


--

C. Boyd
76 Crestmont
East Tennessee

[rallymaster--- via Gmclist]

What is the engine battery voltage with and without the engine running?

RonC

> > James,
> >
> > Digital meter has 20v & 200v setting. Checked all on both settings
> and get
> > the collosing:
> >
> > Battery showing 12.5 volts with ignition off.
> >
> > Engine running- alternator is showing 34 volts output on red wire
> coming
> > from back of alternator to center post of isolator box.
> >

> > Samuel
> > --
> > Samuel Ferguson
> > Pittsfield, Illinois
> > (West Central Illinois)
> > 1976 GMC Palm Beach (A newbie who will not allow this thing to
> kick my
> > butt!!)
> >

> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

Ron & Linda Clark
North Plains, ORYGUN
1978 Eleganza II

[Charles Boyd via Gmclist]

Ken and all, earlier He said battery acc fuse was blowing? And didn't you say it was the circuit going to to the boost switch? In looking at the
X7425 73-74 (6y-19) manual cause it has more stuff about alternator circuit, it shows a drawn picture of the 2 wires going to small plug. It shows a
straight 12 volts to #2 and a wire coming off the ignition switch going thru a resistor going to #1 and is marked "acc"?? Is this the same circuit
that is blowing the fuse? Or would the alternator overcharging blow the fuse or could the resistor wire be causing the overcharging even tho it
checks with a VOM as it should?




C Boyd wrote on Sat, 21 September 2019 21:33

[Samuel Ferguson via Gmclist]

Engine battery voltage engine running/not running is 12.5 volts

[Samuel Ferguson via Gmclist]

The aux battery/radio fuse (10 amp fuse) is blowing.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[rallymaster--- via Gmclist]

I think Ken H. is correct. that could result in overheating a wire, thus
causing a fire. check the diodes in the isolator, and replace it if
needed. Should be about 0.7 volts between center
bolt and the outside ones. Somebody makes a gizmo that connects in there
somewhere that prevents that, but I don't remember details. If the
voltage is greater than about 0.7 volts, replace the isolator.
www.appliedgmc.com › prod.itml › icOid


Ronc

> > On Sat, Sep 21, 2019, 12:45 PM Samuel Ferguson via Gmclist <
> > gmc...@list.gmcnet.org> wrote:
> >
> > > Yes, I have the conductor from alternator - When engine running,
> I am
> > > showing 34. to 36.9 volts from alternator to center lug of
> isolator.
> > >
> > > The same voltage showing to right side of isolator.
> > >
> > > No reading showing on left side of isolator.
> > >

> > > Samuel
> > >
> > > --
> > > Samuel Ferguson
> > > Pittsfield, Illinois
> > > (West Central Illinois)
> > > 1976 GMC Palm Beach (A newbie who will not allow this thing to
> kick my
> > > butt!!)
> > >
> > > _______________________________________________
> > > GMCnet mailing list
> > > Unsubscribe or Change List Options:
> > > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> > >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

[rallymaster--- via Gmclist]

Engine battery should be about 14 volts with the engine running. Same
voltage running/not running sounds like open isolator diode.

RonC

On Sat, 21 Sep 2019 20:01:43 -0600 Samuel Ferguson via Gmclist
<gmc...@list.gmcnet.org> writes:
> Engine battery voltage engine running/not running is 12.5 volts
>

> Samuel
> --
> Samuel Ferguson
> Pittsfield, Illinois
> (West Central Illinois)
> 1976 GMC Palm Beach (A newbie who will not allow this thing to kick
> my butt!!)
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

Ron & Linda Clark
North Plains, ORYGUN
1978 Eleganza II

[Charles Boyd via Gmclist]

You stated this is your 3rd alternator? Is there any chance you are getting the wrong one? 76 Toronado is what we are looking for. I do think as
Ken that the isolator is bad. I was just wondering is there any chance parts store is giving you a one wire alternator and if it would cause this.
The book says this could be caused by a brush holder grounding or a washer in the wrong place in the alternator. Maybe a chance they have a bad batch
with same rebuilder doing the same thing to a bunch of them?? I just seem Im way over my pay grade on this one.
https://www.gmcmi.com/wp-content/uploads/2014/05/X7425_73-74-maint-manual.pdf







Samuel Ferguson wrote on Sat, 21 September 2019 22:04

> The aux battery/radio fuse (10 amp fuse) is blowing.
>
> Samuel

--

C. Boyd
76 Crestmont
East Tennessee

[Charles Boyd via Gmclist]

Maybe PO has replaced radio and tried to splice radio light to grey wire going to dash lights which I think could be a ground..

Samuel Ferguson wrote on Sat, 21 September 2019 22:04

> The aux battery/radio fuse (10 amp fuse) is blowing.
>
> Samuel


--

C. Boyd
76 Crestmont
East Tennessee

[Samuel Ferguson via Gmclist]

Yes Sir, 3rd alternator. The 1st one I bought, that's how they looked up what alternator would be. 76 Olds Tornado 7.5L.

I have heard the remanufactured alternators are like flipping a coin as to if they will work and/or last.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Charles Boyd via Gmclist]

I have heard that also, I have had good luck getting them rebuilt at local rebuilder.





Samuel Ferguson wrote on Sat, 21 September 2019 22:27

> Yes Sir, 3rd alternator. The 1st one I bought, that's how they looked up what alternator would be. 76 Olds Tornado 7.5L.
>
> I have heard the remanufactured alternators are like flipping a coin as to if they will work and/or last.
>
> Samuel


--

C. Boyd
76 Crestmont
East Tennessee

[Ken Henderson via Gmclist]

Sam (sorry about the "Steve" earlier),

Before you start that engine again, allowing the runaway alternator to do
more damage than it already has,
move the wire from the chassis battery terminal of the isolator to the
alternator (center) terminal of the isolator. Then crank the engine and
QUICKLY check the alternator (and consequently chassis battery) voltage.
If it's not near 14-15 volts, shut the engine down QUICKLY and report
back. I think you'll have corrected your basic problem.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

[Samuel Ferguson via Gmclist]

Ken,

So I understand correctly - connect the engine battery wire (on the isolator box) and the alternator wire (center lug isolator box) together on the
center lug of isolator box, the start engine and test voltage from alternator (red wire) to isolator box and the voltage to battery!!!!

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Ken Henderson via Gmclist]

All correct, but you need to check the voltage from the chassis ground (the
aluminum plate on which the isolator is mounted is a good place) to the
chassis battery+alternator output connection on the isolator. That one
voltage is the only one we're interested in right now, and it's
all-important.

Ken H.

[Samuel Ferguson via Gmclist]

Will do Sir. I will check it in the morning and post the findings.

Thank You Sir,

[Bruce Hart via Gmclist]

Napa part number for the alternator is 213-4022. 27SI
https://www.napaonline.com/en/search?text=213-4022&referer=semantic&se=1
I tried to get new alternator from Bosch but it was only a 63 watt.

I agree with you Matt Napa on line sucks.

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class

[Samuel Ferguson via Gmclist]

Ken,

I moved the mentioned wires this morning. After doing so, I did a quick check of the readings. I got 11.9v on center lug with chassis battery
lead/alternator wire placed together. I also noticed the alternator laboring real hard. I immediately turned the engine off and turned the battery
off. I could smell something getting HOT. I found the alternator to be Very hot to the touch. I switched the wires back to their original places.
Checked the voltage again. 11.9v from battery to the right isolator post.

I started the engine, and am getting 34.4 volts from red wire coming from back of alternator to the center post of isolator. 11.9v to the left lug of
isolator. 34.4v to the right lug of isolator box.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Ken Henderson via Gmclist]

Samuel,

For some reason, we're not communicating well. I'm going to go thru your
message and ask for some clarifications:

Ken H.

On Sun, Sep 22, 2019 at 9:58 AM Samuel Ferguson via Gmclist <
gmc...@list.gmcnet.org> wrote:

> Ken,
>
> I moved the mentioned wires this morning. After doing so, I did a quick
> check of the readings. I got 11.9v on center lug with chassis battery lead/alternator
> wire placed together.

Tell me exactly the two points between which you measure the voltage.

> I also noticed the alternator laboring real hard. I immediately turned the
> engine off and turned the battery off. I could smell something getting
> HOT. I found the alternator to be Very hot to the touch. I switched the
> wires back to their original places. Checked the voltage again. 11.9v
> from battery to the right isolator post.
>

This is one of my confusion points: How many terminals does your
"isolator" have?

Also, what's this measurement "from battery to the right isolator post"?
First off, the only measurement that would make any sense at this point is
from the Ground (-) terminal of the battery. Secondly, most isolators I've
seen are mounted vertically, that is, their 3 terminals (NOT 2) are in a
vertical orientation so "right isolator post" or "left isolator post"
confuses me. It's certainly possible that the orientation of your isolator
has been changed.

> I started the engine, and am getting 34.4 volts from red wire coming from
> back of alternator to the center post of isolator. 11.9v to the left lug of
> isolator. 34.4v to the right lug of isolator box.
>

AhHa! There's that "center post" that I've been worried about! Didn't
recall your having mentioned it, so wasn't sure it existed! :-) Now,
we're getting somewhere. I can only assume that the cable on the Left Lug
leads to the Chassis battery (+) and that on the Right lug leads back to
the House battery. Please confirm that.

Here's what I the information you've shared leads me to believe:

1. The Chassis battery diode in the Isolator failed, allowing the
Alternator to "run away" (and that's happened to every alternator you've
installed since). The open diode is why you read only the Chassis battery
voltage on the Left terminal of the Isolator.

2. One of the runaway Alternators caused the House battery diode to short
due to the high voltage and current overheating it. That short circuit is
why you read the same voltage on both the Center (Alternator) and Right
(House) terminals.

3. The current Alternator has failed, probably due to having run open loop
(with no feedback from the Chassis battery), so that it can no longer be
regulated.

4. If your House battery has not already been irreparably damaged by
excessive voltage, it WILL be if you continue to run that Alternator.

5. You should take the Alternator back to the source and have it tested.
Have any replacement tested before installing it.

6. DO NOT run another alternator without having the Chassis battery
connected directly to the Alternator output, as I instructed yesterday --
that's the surest way to ensure proper feedback to the Alternator and to
prevent damage to other electrical components.

7. Before you plug the two-wire connector into the replacement Alternator,
disconnect the Chassis battery positive lead and measure the resistance
between it and the #2 terminal (White wire) in that connector. It should
be as near zero as the meter can read -- the same as when you short the two
meter leads together. If not, that problem MUST be corrected.

8. Report all these results before starting the engine again.

HTH,

Ken H.

[Johnny Bridges via Gmclist]

Your test voltage and laboring alternator indicate the alternator is looking at a short. The open diode on that battery supports this thought -
something shorted and burned the isolator diode open. This removed the sense voltage from the alternator and it's running away. The hot smell
supports this theory. Now we have to guess. I'm going to guess your power feed to the rear battery is shorted inside the coach wall someplace. To
preclude a shorted cell in the house battery, I would totally disconnect it and try to charge it with an outboard charger. Best approach is probably
one of the cheap ones that provides 6 amps or so, and run it overnight. If the battery charges and holds a charge, go looking for a shorted wire
feeding it. First suspect is the large size wire running to the rear solenoid and the 12 volt panel. If it doesn't hold a charge, it is suspect for
having a shorted cell internally. Pull it out and have your parts house check it. Report back.
There is no need to continue ruining alternators, heal the trouble first.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

[Samuel Ferguson via Gmclist]

Ken,

I will try my best to clarify!!! I attached photos to your email for your review.

The isolator box is a 3 plug type . The way it is mounted and the way I was told to describe it - center plug (top)

top plug (left)

bottom plug (right)

Yes, the left lug goes to the center post where the "sticker" on the firewall says "Vehicle Battery Positive". The right lug goes to the left side of
the solenoid which is mounted directly below the isolator box.

After moving the chassis battery wire (top left) to the center lug - I checked and got a reading 11.9v. I started the engine and did a quick check
and got the following:

Alternator was laboring real hard. I immediately turned the engine off and turned the battery off. I could smell something getting HOT. I found the

alternator to be Very hot to the touch. I switched the wires back to their original places. Checked the voltage again. 11.9v from battery to the right
isolator post.

I started the engine, and am getting 34.4 volts from red wire coming from back of alternator to the center post of isolator. 11.9v to the left lug of
isolator. 34.4v to the right lug of isolator box.

Thank You Sir,

Samuel

--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Samuel Ferguson via Gmclist]

Johnny,

I did fond the booster cable to have coating missing from it along the framing behind the grill area. I have unhooked the booster cable from the
solenoid on the firewall engine compartment. I checked the cable to the connections block located behind the converter and found the cable to appear
to be in working order (no other shorts/grounding) other than what I found it to be touching the frame behind the grill. I have insulations material
ordered to recover the exposed sections (which is approx. 3 feet). But for now the cable is unhooked and no power running to it. My house batter y is
new and it is still holding a charge.

Samuel
--
Samuel Ferguson
Pittsfield, Illinois
(West Central Illinois)
1976 GMC Palm Beach (A newbie who will not allow this thing to kick my butt!!)

[Johnny Bridges via Gmclist]

OK. Let's let Ken H take the lead on this one to preclude any confusion. I'll make one recommend though. If the cable has she3d insulation where
you can see it, it probably had where you can't as well.I'd plan on replacing it. You will likely have to run the replacement inside the frame rail,
it's not really possible to follow the initial routing without removing stuff inside the coach.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

[Ken Henderson via Gmclist]

Samuel,

I got your email with the photos. That's a REALLY old isolator. I don't
think I'd ever seen a real, OEM, GM labelled one before! Too bad you're
probably going to have to replace it. But before you do, you should test
it, both to ensure that it's really bad (or good) and to let you learn a
little about them. Before we get into details of that, let's agree to quit
using those meaningless terms "top, bottom, etc." and call the terminals
what they are: The middle terminal is for the Alternator. The other two,
when disconnected, are identical in function, so when connected, they
become either House or Chassis terminals, indicating which battery they
serve.

To test the Isolator, since I know you have a multimeter, use it. With the
lowest Ohms range selected, touch the two leads firmly together and be sure
the display reads at least close to zero. When they're not touching, it
should read as high as it's capable of -- "infinity". Now, with all leads
disconnected from the Isolator:

1. Put the Positive (should be Red) lead on the middle terminal and the
Negative (should be Black) lead on one of the other terminals.

2. Note the meter reading. It should be nearly zero or nearly infinite.
Remember that.

3. Now move the Negative lead to the other terminal, keeping the Positive
one in place. Read the meter again and remember what it says. It SHOULD
read the same as before; if not, the Isolator IS bad. We'll find out which
side in the next step.

4. Swap the locations of the leads (Negative to the middle terminal) and
do the same two tests you did above. Anywhere you read zero before SHOULD
now read infinite and vice versa.

5. If either test does not reverse its reading, the diode between those
two terminals is bad. If the unchanged reading was zero, the diode's
shorted; if infinite, the diode's open.

6. If there's not a defective diode, the Isolator should continue to work
fine. Otherwise, buy a new isolator.

But while waiting for a replacement Isolator, you can continue with all
other tests -- remember that the ONLY thing the Isolator does for you is
prevent the batteries from being drained together when the engine's not
running. And it's not even needed with the Sense lead connected to the
Alternator Output.

Johnny's already given you some hints about checking for shorts. IIRC, you
already tested the circuit from the House battery to the Boost solenoid and
repaired the deteriorated insulation on that cable. If not, complete those
tasks now. Since you've repeatedly reported seeing the same voltage at the
Chassis battery and at its connection to the Isolator, I'm confident that
circuit is in good condition. However, the reported voltage is that of a
DEAD battery, which makes me ask, "How did you start the engine?" The
answer to that may be significant.

Ken H.

[Emery Stora via Gmclist]

From your description it sure sounds as if your isolator is the problem.
If you keep experimenting you are going to burn out your alternator .
Do you know how to check your isolator with a vom? it is very simple.

Emery Stora
77 Kingsley
Frederick, CO