ELECTRICAL Ground Issue

[grant schaffer]

So I am replacing the cables to the starter and the battery and I reconnect the ground and the small cable that runs to the passenger floor well in
the engine bay up front gets hot and melts when the ground on the battery is connected.

Anyone have any thoughts?
--
1974 GMC Sequoia 26'

 

[Ken B]

I am not sure what small cable you are talking about that is burning.

There are suppose to be two cables connected to the Negative side of the battery. Ones is a heavy 4 ga. Black one that goes direct to the engine
block and is attached to a bolt near the right side exhaust manifold. I believe its is really a stud and nut but could be wrong. The second cable
attached to the negative battery terminal is a 14 ga. black wire that goes to the aluminum plate under the passenger side hood that the isolator and
boost solenoid / relay are mounted on.

The positive of the battery should have a red 4 ga cable going to one side of the boost relay that is mounted on that aluminum plate.

If you can give us a better description on what wire is burning we will try to help. You obviously have a short somewhere.

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

 

[grant schaffer]

Ken
Seems to be the 14 ga wore that attaches to the coach with a bolt on the back side of the glove box
Grant
--
1974 GMC Sequoia 26'

 

[Ken B]

We may be talking about the same thing. When you say "back of the glove box", are you seeing it attached from looking inside of the glove box door,
or are you seeing it by opening the passenger side outside hood and looking straight ahead, and a little below eye level at a piece of aluminum
plate?

Which wire is burning?
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[john r. lebetski]

Skinny negative is doing the work of the heavy black one or trying to. Double check the heavy one to the block. Also there should be a flat braided
one to body rear of engine. With a meter you can do voltage drop testing and find the resistance, but sounds like main ground connection from
battery to block. Block is the home plate for grounding, called star ground. Could be a faulty new neg cable where they crimped over insulation?
It’s 2020 gotta prove new stuff is actually good not defective.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[jim kanomata1]

Like John mentioned, the grounding straps are very important.
The Majority of the mechanics never connect the ground , so you end up
doing it yourself.

On Sat, Jul 4, 2020 at 11:23 AM John R. Lebetski via Gmclist <

> Skinny negative is doing the work of the heavy black one or trying to.
> Double check the heavy one to the block. Also there should be a flat braided
> one to body rear of engine. With a meter you can do voltage drop testing
> and find the resistance, but sounds like main ground connection from
> battery to block. Block is the home plate for grounding, called star
> ground. Could be a faulty new neg cable where they crimped over
> insulation?
> It’s 2020 gotta prove new stuff is actually good not defective.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502

 

[Ken B]

> Skinny negative is doing the work of the heavy black one or trying to. Double check the heavy one to the block. Also there should be a flat
> braided one to body rear of engine. With a meter you can do voltage drop testing and find the resistance, but sounds like main ground connection
> from battery to block. Block is the home plate for grounding, called star ground. Could be a faulty new neg cable where they crimped over
> insulation? It’s 2020 gotta prove new stuff is actually good not defective.

John,
I still do not understand if that "skinny negative" wire is the one he is burning. Does it burn when starting the engine with a high current draw? I
read that he hooks up the negative battery cable and it burns the wire. Which wire and under what operating conditions?

In a properly wired coach that "skinny negative" wire should not burn
even with the main "heavy negative" battery cable disconnected. This is because there in no other circuit wired back to the master ground (the
engine) from the aluminum grounding plate behind the passenger side hood. So if that is what is happening, then he has wired himself a ground loop
somewhere associated with that plate and it also needs to be cleared.

I suggest that we do not have an enough information at this point to make a good diagnosis.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Jim Hupy]

That's why I have stayed out of this thread. The guy is only giving us a
tiny bit of the picture to look at. You have already asked him two or three
times for more info. Cannot give him much help with what he has provided so
far. Hope he doesn't burn his coach to the lugnuts in the meantime..
Jim Hupy
Salem, Oregon

On Sat, Jul 4, 2020, 12:58 PM Ken Burton via Gmclist <

> > Skinny negative is doing the work of the heavy black one or trying to.
> Double check the heavy one to the block. Also there should be a flat
> > braided one to body rear of engine. With a meter you can do voltage
> drop testing and find the resistance, but sounds like main ground connection
> > from battery to block. Block is the home plate for grounding, called
> star ground. Could be a faulty new neg cable where they crimped over
> > insulation? It’s 2020 gotta prove new stuff is actually good not
> defective.
>
> John,
> I still do not understand if that "skinny negative" wire is the one he is
> burning. Does it burn when starting the engine with a high current draw? I
> read that he hooks up the negative battery cable and it burns the wire.
> Which wire and under what operating conditions?
>
> In a properly wired coach that "skinny negative" wire should not burn
> even with the main "heavy negative" battery cable disconnected. This is
> because there in no other circuit wired back to the master ground (the
> engine) from the aluminum grounding plate behind the passenger side hood.
> So if that is what is happening, then he has wired himself a ground loop
> somewhere associated with that plate and it also needs to be cleared.
>
> I suggest that we do not have an enough information at this point to make
> a good diagnosis.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
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