Help! Crazy Electrical Problem!
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Newbie
Joined: Feb 2008
Posts: 1
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1993 MB 300E 3.2
Help! Crazy Electrical Problem!
Jesus I don't even know where to begin. 1993 300E 3.2.
Had the car about 1.5 years now and it has been mostly fine But a few months after I bought it, the indicator light for "light out" started coming on intermittently when I pushed the brake pedal. It would come and go.
Fast forward a year and a half. Fuse #3 starts blowing all the time. This fuse controls rear tail light on right side, instrument cluster lighting, HVAC lighting, window button lighting, etc. Put in a new fuse and when I flip on the lights, it blows. Keep lights off and it's OK.
I removed the rear light panel on the right side. Disconnected it from harness thinking this must have been the problem because the dummy light went on when I hit the brake pedal. Put in new fuse. Still blows fuse when light goes on.
A few months ago this problem led me to remove the instrument cluster and mess around with the rheostat but I put it back in and it seemed to be just fine. I am just completely out of ideas.
Anyone?
Had the car about 1.5 years now and it has been mostly fine But a few months after I bought it, the indicator light for "light out" started coming on intermittently when I pushed the brake pedal. It would come and go.
Fast forward a year and a half. Fuse #3 starts blowing all the time. This fuse controls rear tail light on right side, instrument cluster lighting, HVAC lighting, window button lighting, etc. Put in a new fuse and when I flip on the lights, it blows. Keep lights off and it's OK.
I removed the rear light panel on the right side. Disconnected it from harness thinking this must have been the problem because the dummy light went on when I hit the brake pedal. Put in new fuse. Still blows fuse when light goes on.
A few months ago this problem led me to remove the instrument cluster and mess around with the rheostat but I put it back in and it seemed to be just fine. I am just completely out of ideas.
Anyone?
Super Member
Joined: Feb 2008
Posts: 844
Likes: 1
From: Orland Park, Illinois
1994 E320 (current)
Electrical problem.
I used to work at a benz dealership as an apprentice tech. We had a car doing the same thing and had to trace it for 6 hours to find the issue. It was in the wiring harness where the guy who owned the car used DRYWALL SCREWS to screw down the floor mats to the floor in the back seats. What he didn't realize is the brake light harness ran directly under the floor liner. He frayed a wire and whenever he hit the breaks it blew the fuse because he had bare wire touching off directly to the metal floor pan. You should always start on the other end at the brake lights and work your way back to the cluster. You most likely have a bare wire. Pay special attention to the areas where the wire transitions under moving parts (seats, etc.) a good roll of electrical tape will come in handy because you may find other friction areas on your harness that you can fix up while your in there.
Hope this helps.
Gary
Hope this helps.
Gary
MBWorld Fanatic!
Joined: Feb 2006
Posts: 1,325
Likes: 2
From: Seattle
1990 300ce
your model is one of the 124's that was plagued with the wiring harness issue.
There are literally thousands of posts on this subject on the MB forums (check mercedesshop.com too), so search around and you'll find all the info you need about symptions/fixes/etc. Do you know if your wiring harness has ever been replaced?
There are literally thousands of posts on this subject on the MB forums (check mercedesshop.com too), so search around and you'll find all the info you need about symptions/fixes/etc. Do you know if your wiring harness has ever been replaced?
