1987 300TD Electrical Problem...
 

Have encountered an electrical problem with my 300TD that may have it's roots in a problem I've had for a couple years...

For about the last two years, the exterior lamp failure dash light has been illuminating the instant I turn my parking lights on. I have checked outside countless times and there were not any exterior lights blown.

Fast forward to a week ago- the dash cluster nighttime illumination lights stopped working. Initially I thought the rheostat was broken. Then I noticed the right side front and rear marker lights AND the headlight wipers had stopped working. Aha!...must be a fuse...lo and behold the #3 fuse was blown. I replace it and confirm the dash cluster and side marker lights work properly...for about 10 seconds...and the fuse blows again. I replace the fuse a second time, and this time it blows immediately with a flash.

Is there a relay in the lamp monitor system somewhere that could possibly be causing ALL these problems??

J.G.

I had a similar issue on my SDL. The wiper motor on the right hand side was the issue, there's a control circuit that pukes in it and causes a dead short. Insta-blows the fuse, which is annoying because it takes out the marker lights! I unplugged the wiper motor on that side and haven't had a problem since.

Hopefully it's a seized electrical motor, but it's possible you have a short to ground. Look around areas of HEAT, VIBRATION and METAL contact. Sometimes wires will short out through a routing hole with a missing or non existent grommet.