Electrical melt down

[72GMC51]

My 72 GMC was basically finished, when I started to have an exhaust type smell in the cab with the air on.
Then I noticed my battery was boiling over.
Turns out a post on my factory blower switch was loose causing resistance.
It looks like it caused possibly multiple electrical problems.
One of the fuses on my cooling fans was blown the other distorted but not completely blown.
Blower fuse was badly warped but not blown.
Now. Have a parasitic draw on my electrical system, I have basically disconnected or unplugged every electrical device in the truck but still have a draw, which is as high as 26 amps, after I disconnected most everything I could fine was still at 12amps.
I have vintage air heat/cool system.
I have attached a couple of pictures.
Truck was working like a dream, now I have it half apart again.
🤪😡😭

All wiring and switches (except blower switch) were replaced.

[Baddflash]

double post

[Baddflash]

12amp draw is huge, even the 26amp constant with nothing running is way too high. Something must be getting hot drawing that much current. How are you measuring the current draw by the way?
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[gmc684x4]

It is very fortunate that you caught it when you did

I would replace all wiring with new harness
Keep going through the trouble shooting the draw 26 amps is a big draw in the off state something major has shorted out or more specifically many things now have potential shorts to ground

Any connectors that are blackened have a much greater chance to have a path to ground through carbon tracking

Make a list on how your troubleshooting the parasitic draw and yes how are you measuring amp draw

[Dead Parrot]

Boiling battery suggests a bad voltage regulator or resistance on the voltage sense wire(depending on alt version) that caused an over volt condition. The over voltage may have caused the other problems.

Possible the current drain is through the alternator.

[VetteVet]

You must have a direct short to ground to cause a 26 amp draw and even 12 amps is too much. DP is correct about the battery and the alternator and a short like you have could also cause the battery to boil. I don't see how you can even connect the battery without large sparks at the terminals and you have to be very careful because it could explode.

Like Baddflash I'm curious how you measured the current draw.

GMC makes a good point about the tracking of the burnt connectors They will lead you to the short.

keep us informed about your progress. Feedback is important to others with similar problems.

[72GMC51]

.26 and .14 amps
not 26 or 14 amps
Sorry
ACGoodwench

[72GMC51]

I am checking the amp by disconnecting negative battery cable amp gauge hooked between cable and battery. all electrical off.

[gmc684x4]

0.26 amps is low 26 is very high
at 26 amps yes you would have a large sparks connecting the load
Can you take a picture of how you are measuring it

Yes Over voltage can melt down your harness
besides carbon tracking the melted harness will now also be a fire hazard
The burned connections will increase resistance which will increase amperage

At the very least i would replace the under dash harness the headlight harness and the engine harness and any other sections that show signs of meltdown

Do you know what voltage the alt was putting out ?

Which type of alt is it and how is it wired ?

[72GMC51]

This is how I have it hooked up. Now it’s doing all kinds of weird ****. I hooked up the wiring harness and re-tested and now the numbers are all over the board and that’s with most of interior electrical switches disconnected.
I do believe that replacing harnesses may be necessary.
🙁

[72GMC51]

Alt hook up!
How cam I upload a video?
JC

[gmc684x4]

Is that a cs 130 altenator?
Did you add a resistor to the L terminal ? Did you use any other terminals on the alternator?

With so many of the connections melted and burnt i am not surprised the readings are all over the place