Electrical Issue

Willem Tell

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Note to self, disconnect the battery when working cleaning up previous owners's electrical stuff.
Your car can injure, burn or kill you. I know a few people who have gotten 3rd degree burns from their watch grounding, gets hot fast.
Amen! I once saw the hand of a friend who had just after he accidentally got his wedding ring stuck between the starter 12V lug and the engine block. The wedding ring vaporized along with much of his skin. It was not a pretty sight! The wedding ring stays on the kitchen counter until I've finished my car work for the day!
 

HB Chris

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Don to the rescue! We many times ignore the simple solutions like removing battery positive terminal, clean and tighten it up. Bingo! I can now proceed at a slower pace to trace and remove the melted ground wire until I find where it shorted. It is not a trivial process and I do not look forward to it but it must be done.
 

Krzysztof

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Can you measure the resistance between battery terminal (not connected to battery) and ground?

If so and the resistance is low (below 50Ohm typ.) you may try to use continuity tester (beeper) to play with wiring and check if this behavior is not intermittent causing "beep" sound to stop once you will touch the part of the wiring where the short to GND is. Typically it may be on the edge of firewall, rubber boots leading the wires (like doors) or regions with many wires.

Quite often is multiple wired are crimped into one they got loose and sliding out.

Sometimes due to pulling force, repair, heat or age part of wire isolation is going up, showing more copper which can easily touch GND being available in many places/wires/nuts...

Maybe that help
 

Ohmess

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Hi Chris - You probably remember this, but because your Chamonix car is an older model than your Malaga car I'll mention this again. On the earlier version of our cars, there is unswitched power distribution in the fuse block between fuses 4 and 5, and switched power distribution between 6 and 7. The obvious point of this is when you pull fuse number 4, all the upstream stuff from fuse 5 and more importantly all the downstream stuff from fuse 5, is still connected to the upstream stuff from fuse 4.

You need to take this into account as you do your continuity tests to try to chase down the damage from your melted wire.
 

HB Chris

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Hi Chris - You probably remember this, but because your Chamonix car is an older model than your Malaga car I'll mention this again. On the earlier version of our cars, there is unswitched power distribution in the fuse block between fuses 4 and 5, and switched power distribution between 6 and 7. The obvious point of this is when you pull fuse number 4, all the upstream stuff from fuse 5 and more importantly all the downstream stuff from fuse 5, is still connected to the upstream stuff from fuse 4.

You need to take this into account as you do your continuity tests to try to chase down the damage from your melted wire.
Both coupes are May 73 and the 72 diagram is the same but I use the 74 one only for breakers and window motors.
 
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