More Electrical Fun - PeachParts Mercedes-Benz Forum

avenueplayer · #1 02-07-2006, 12:05 AM

I've been tangling with random electrical faults in my '80 300SD, which I bought a couple of months ago. It had been sitting for 4 years, so I expected some problems. Aside from cracked belts, bad starter, etc., there seem to be some electrical problems. The previous owner claimed that electrical problems started right after the stereo was stolen. Anyway, the blower motor was working just fine until this weekend when it just didn't start up when I pressed the switch. It wasn't cutting out or anything like that before.

I gave it another try today and after the third try I heard a muffled pop behind the instrument cluster. A split second after the pop, the glowplug light came on for the same amount of time that it normally does when I turn the key to pre-glow.

I won't be able to pull the cluster until the coming weekend. I do have some blower motor brushes coming in the meantime, but my patience is getting the better of me. Has this happened to anyone before? Thanks for any wisdom anyone can share.

Ralph69220d · #2 02-07-2006, 09:27 AM

Did the blower motor also come on when you heard the muffled pop?

avenueplayer · #3 02-07-2006, 10:21 AM

Quote:

Originally Posted by Ralph69220d

Did the blower motor also come on when you heard the muffled pop?

It stayed off and hasn't come on since.

avenueplayer · #4 02-11-2006, 08:10 PM

Looks like it was most likely the blower motor brushes as I was able to get to the fan and give it a whack. It turned on and off a couple of times, then went dead again. I got new brushes and will put them in when I have a chance.

BUT...

The reason I was down in the passenger well was to see why I have no kickdown. I decided to have a look at the kickdown solenoid to see if it was ok. Sure enough, the board was burnt out right past where the #2 pin attaches to it. I carefully went over it with a little solder to see if it'll do anything. I reattached it, turned the key and all of the instruments & warning lights went out. I blew fuse #4 (8 amp). Tried a 16 amp fuse in there and blew it too. The warning lights and gauges worked once I stuck a 25 amp fuse in there. Still no kickdown.

I still haven't tested the kickdown switch itself, but I'm more concerned about what's causing the fuse to blow. Anyone have any ideas?

avenueplayer · #5 02-13-2006, 01:56 PM

Quote:

Originally Posted by avenueplayer

The reason I was down in the passenger well was to see why I have no kickdown. I decided to have a look at the kickdown solenoid to see if it was ok. Sure enough, the board was burnt out right past where the #2 pin attaches to it. I carefully went over it with a little solder to see if it'll do anything. I reattached it, turned the key and all of the instruments & warning lights went out. I blew fuse #4 (8 amp). Tried a 16 amp fuse in there and blew it too. The warning lights and gauges worked once I stuck a 25 amp fuse in there. Still no kickdown.

I still haven't tested the kickdown switch itself, but I'm more concerned about what's causing the fuse to blow. Anyone have any ideas?

Anyone?