One thing I thought when I got this truck, after looking under the dash, was “I hope I never have to mess with the wiring”.
On rare occasions, this truck would act flaky with the electrical systems, headlights wouldn’t turn on or difficult to start, but it was always brief. I did get a three lever switch at one point, but the problems never really occurred that I noticed after this.
After the rebuild, and driving it for a bit, I noticed the service lights were flaky and I didn’t have turn signals. I got it home and discovered a fuse was melting but not blown. I poked around for a bit and decided to stop driving it since something electrical not working right is a great way to start a fire. A good thing I did, since I found what was likely the foundational issue, the main battery cable sheathing had worn through in multiple places and was arcing on the truck somewhere. The wiring in general is about 20-70 years old and probably could benefit from a refresh so I am doing a rewire. There are wiring harnesses out there for sale, but all of them assume a fairly standard M37, which mine is not. Its a 24-12v conversion with some extra items that aren’t on a standard M37, a siren, cab heater, and whoopee light for instance, as well as some engine modifications to the ignition system that make going back to 24v impractical.
Ill post about this project as I complete systems to document my experience.