Electrical problem - 280sl 107

[Steve C]

Group

The instrument cluster reading stopped while driving the
car. spedo, tach, odometer, oil, temp are all out.

The only item that works is the battery indicator light goes
on when starting up and then goes off. Clock also runs.

Breaklights, power windows, turn signals are also out.

Headlights and tail light work. Door locks work also.

Checked fuses with a flashlight and no breaks seen.
Dont understand the fuse #'s as its in German.

There has been a rare loss of spedo and odometer in the past and the
back-up lights have been problomatic.

Is this a wiring harness problem?

Many thanks to all

Steve, '84 280sl 5 speed stick, 192k

[rowdie]

I have read where the ground bridge across the cluster can cause a myriad of problems. Pulling the cluster, cleaning contacts and adding a ground wire to the chassis can solve it. My '81 280 all of a sudden stopped charging and this was the problem.

A second thing I have experienced is that the older model fuses have alloy contacts that while they may look good the contact points can corrode (can't remember what it is called when two different metals are in contact, damn my old memory). Cleaning them and the copper contacts will be a PITA but might be worth a try. Also replacing with newer copper fuses might help.

These are the easiest fixes I can think of. Maybe others will chime in. Good luck.

[Strife]

If you have an electronic speedometer, a short to the cluster can blow a trace on the speedometer printed circuit board, causing many problems. This can be repaired (I did this with a 500SL Euro speedometer). This PCB is under the white plastic cover. The break is towards the bottom and it should be obvious.

[Steve C]

I went back and checked the fuse chart
and read the words a little more and figured
that it was fuse #7 that controlled the instrument
panel.

Pulled out #7 and saw that it was blown at the end and
replaced it. All started up ok and did a two mile test run
and all worked again including the speedo, windows,
breaklights etc.

Im one lucky and happy camper!

thanks to all for their thoughts and advice

Steve

[meltedpanda]

good for you !, but yes traces and grounds can cause these issues, I have had both on mine