Overheated Ammeter

The last time I had the truck running, the ammeter all of a sudden got real hot and I noticed a smell like burning insulation. I took the gauge out and see no visible damage to it, or to any of the wiring. The whole wiring loom is new, from Rhode Island. The truck had been running for about 20 minutes or so - the first time I had had the engine running for that long, I think. Any ideas on where to start looking?

Thanks, David
 
Check to be sure the nuts holding the wire on are tight. Also check to be sure that the terminals on the back of the ammeter are not grounding out on the gas tank.

Charlie Stephens
 
This happened to me about 4 months ago. Had a dead short which fried the ammeter (an original !). Found that my terminal box brass screws were in direct contact with the firewall. I replaced the terminal box and the ammeter. No problem since then.
 
The terminal box issue has been around with repop boxes made in the 1980s. Original terminal boxes don't have the problem New Repop boxes have seemingly gotten past the issue.

Many put a layer of cardboard or other insulator between the terminal box and the firewall.

And one might do well to check the internal of an ammeter. Subject to a similar "tightness" issue to the exterior nuts, the issue is the same where the stud contacts the bridge - it's just harder to deal with.

Joe K
 
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