Hi all,
I've been chasing an electrical problem on my '75 W200 for a while now. Here's what is going on, the truck will turn over and start right up 90% of the time. Then for no apparent reason at all, I will get absolutely no power to the starter, ignition, lights, or anything. The battery still reads 12.7v, but nothing works. At first, removing and cleaning the battery terminals fixed the problem temporarily, but now nothing seems to help. Today I had it idling in the driveway and the lights went out it just died (no sputtering). I let it sit for an hour and then tried again and it fired right up, idled for 2 minutes and then died again and I haven't been able to get it started since. It doesn't turn over, I don't even hear the starter solenoid click. Is there something common I should be looking for? Thanks in advance.

 

did you check for 12volts at the starter. there is 3 wires hooked up to the positive terminal. the starter, 4ways and the main power wire that hooks up to everthing. sounds like you may be having some problems with the main positive power wire that powers everthing.

 

I have 12v to the starter relay, but I didn't test anything else.
Its not just that I don't have power to the starter, I have power to NOTHING. I'm thinking it might be something related to the three plugs mounted to the firewall on the drivers side of the engine bay. Can anyone tell me what's connected to the left hand plug (as you're sitting in the drivers seat) on the fire wall? I know the lights and the window washer motor travel through that plug, but what else? Thanks.

 

Well, I got it figured out. Turns out I was right about the plug on the firewall. A wire running from the starter relay to the ignition runs through a plug that had a few spades broken off so it wasn't getting a good connection. I bypassed the plug and soldered the wires together and everything works like a charm now.