OK, hopefully I'll have more time on Saturday to charge the battery and do the test as you described. Getting the battery charged can be a pain in the butt, since I either have to lug the battery inside or run extension cables out my window and across the sidewalk! I didn't have much time to work on it last night, but I spent some time looking at the wiring diagrams and tracing the cables that run from the alternator to the battery, trying to figure out what I could test without the engine running. There is a heavy gauge wire that connects the positive terminal of the battery to the starter. From there, there are two wires that connect to the alternator's B+ terminals. There is also a thin blue wire that I believe connects up to the idiot light. With the engine off, I put the negative lead of the volt meter on the negative terminal of the battery, and tested the voltage at the starter connection, and the wires that run to the alternator. I read ~12V at all points... which means that I at least have some continuity. That still doesn't rule out a high resistance problem, as you mentioned. Rather than test for a voltage drop with the car running, would it make sense to measure the resistance of the wires directly using the ohmmeter function of my multimeter? What about that blue wire that goes up to the instrument cluster... could a problem with that wire prevent the alt from charging my battery?

Thanks,
Nate

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1985 300DT, Classic White, California, 175K
1984 300TD, Classic White, Euro, 285K


"When nine hundred years old you reach, look as good you will not. Hmm?" - Yoda