I've been getting a 1985 S10 Blazer running that sat for several years, and I've gotten almost all of the electrical system working again. The under-dash lights come on when you open the doors or turn the headlight **** counterclockwise. I work in electronics, so I've taken a lot of measurements. Both the lighter socket and the horn have power, and according to the shop manual, they should be on the same circuit as the dome and cargo lights.

I have no 12V power OR ground connections at the dome or cargo lamp terminals under any conditions. With the battery disconnected, I find effectively infinite resistance (~5 Meg Ohms) between the light fixture terminals and both the 12V source and ground. It's like those fixtures are totally disconnected from the rest of the car's electrical system.

The question is: Where to look for the fault? It looks like there's an 8 wire harness that runs from the back to front and plugs into an 11-pin connector -- somewhere, and a 2-pin connector for the dome lamp that plugs into that same 11-pin connector. That seems like it would be a good place to start looking.

So where is that connector? Under the carpet? Behind the dash? What am I going to need to disassemble to find it?