Henry's 70 Dart Swinger

The problem commonly occurs from years of weather and moisture exposure to the terminals on the bulkhead connector. You get corrosion followed by resistance and that adds up to heat.

On my Swinger, I installed a volt meter and bypassed the wiring to the ammeter under the hood with a 10 gauge wire from the alternator to the starter relay. You should also install a fusable link in-line with that wire.

I had also done this previously on a B-body I recently gave to my son. The underdash wiring cooked when the ammeter wire melted and shorted at the bulkhead connector and overheated the entire length of it. I had to rewire the underdash. We have a donor car for that B-body with the same problem which is likely why it was retired. Photos below.

If you really want to keep the factory ammeter functioning then you need to bypass the bulkhead connector with the ammeter wires ( and increasing the gauge) and run them directly through the firewall in their own dedicated grommets and then up to the ammeter. Early 70's Chrysler fleet vehicles had this setup due to the increased load demands on the wiring harness. If you look at wiring diagrams in B-body factory manuals, you will see how this is wired with a note indicating "Fleet" or "Heavy Duty".

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