560sl Instrument Cluster Wiring - PeachParts Mercedes-Benz Forum

jwedeven · #1 04-30-2007, 08:13 PM

I recently removed the instrument cluster to have the odometer repaired. When I re-installed the cluster I discovered a problem with the gages. The lights work but when I hit the turn signal the gas & oil pressure gages "blink" also the gas gage shows the tank full. I suspect that the multi-pin connector is not lined up right. Any help on the "right orentation"?

Nascar Fan · #2 04-30-2007, 09:12 PM

It is more likely to have put your lamp sockets in the wrong holes on the cluster. With the cluster half out, turn the turn signals on and then plug the light is the correct hole. I think they all have matching numbers if you can read them.

jwedeven · #3 05-02-2007, 03:23 PM

Thanks, you are right there are several lights and I have them in the right socket. I still think that there is something that I need to get right with the "multi-pin" connector from the wiring harness to the instrument cluster.
JWedeven

Roncallo · #4 05-02-2007, 03:46 PM

Well I sure am interested in this problem. I removed my instrument cluster to repair a WW transmission and now with the lights on all of the left side gages go to full scale. With lights off they blink to full scale with the turn signals on. Everything seams crossed like the guy who turns on the shower and his sink comes on. I thought for sure it was indexing of the multi pin connecter but I looked at it and it is correct.

If I find anything I will let you know.

John Roncallo

Nascar Fan · #5 05-02-2007, 05:20 PM

There is a ground wire that NEEDS to be connected from the cluster back to the frame. It will likely fix your problems.

nobby · #6 05-03-2007, 01:24 AM

The ground is included in the harness but an ADDITIONAL ground from the cluster to the underdash framework is a highly recommended by .....well...me and Nascar.

Roncallo · #7 05-13-2007, 04:44 PM

After looking into the ground theory I decided to go a step further and find where is the broken ground and can I fix it. Keep in mind this is a 1988 560SL.

First After looking at the wiring diagrams I found that ground comes into the instrument cluster via the 3 pin harnass (4 pins only 3 used) on the back of the speedometer.

First step was to verify pin #1 of this harness was grounded to the chassi. This was done by putting an ohm meter between pin #1 of the harness connector and a good grounding point on the chassi. See the first photo. In my case the ground was complete.

Next was to see if ground was connected to the left side gages which seemed to be the effected gages. It was obvious that ground got to the left side gages through a metal ground strap located on the screw hole on the top right of the spedometer when looking at the cluster from behind. Pin #1 from the harness connects to pin #31 on the back of the speedo. See the second and third photos. In my case I had no continuity between pin 31 and the screw on the top right corner.

I removed the spedometer from the plastic back and found the broken circuite path. See the bottom right corner of the 4th picture.

I repaired the break as shown in the 5th picture with a jumper wire soldered in place, bypassing the effected area.

All working well now.

And yes, the easyier way to do this, would have been to just take a wire from any convinient chassi ground and put it to one of the screws on the metal tachometer side of the instrument cluster.

John Roncallo

nhdoc · #8 05-13-2007, 05:15 PM

I also had this same issue and posted a response similar to yours some time ago:

Instrument problems

Roncallo · #9 05-13-2007, 07:54 PM

That very cool. I tried doing a search on this problem but was unsuccesful. I guess I did not know how to describ it. I see yours broke in the same location as mine. That must be MB idea of a fuse.

John Roncallo

nhdoc · #10 05-13-2007, 07:56 PM

Quote:

Originally Posted by Roncallo

That very cool. I tried doing a search on this problem but was unsuccesful. I guess I did not know how to describ it. I see yours broke in the same location as mine. That must be MB idea of a fuse.

John Roncallo

Yeah, it is the thinnest part of the tracing on the PC card so it must be the first to break over the years of use.

BabyBlueBenz · #11 01-19-2009, 09:32 PM

...Roncallo and nhdoc, for your helpful posts on this vexing problem.

After removing my instrument cluster to repair broken odometer gears ($69 from odometergears.com), I managed to ground the always-hot clock lead during the reinstallation. I saw it happen, but didn't think it caused any harm.

Well, with the cluster back in and the steering wheel back on, I experienced the exact same behavior as described by jwedeven's post that started this forum thread. I then knew both the cause and the solution.

As the before-and-after attached photos show, I also had the "fusible trace" on the back of my speedometer melt (as well as the #12 fuse blow). I installed the prescribed jumper and now all is well in instrument-cluster-ville.

To anyone considering the removal or re-installation of their instrument cluster: DISCONNECT YOUR BATTERY FIRST!

vonstro · #12 07-20-2017, 09:16 PM

Having read your post I thought it appropriate to send you this short note explaining a problem that's unique to us both. I too had the problem you spoke of pertaining to the odd dash light behavior. The problem I had was in fact caused by misplacement of the multi-pin connector. As is was the case with my connector the placement pin in the center of the male plug had been broken off at some time in its past life. I wasn't aware of this and misplaced the plug the first time I reassembled things. I wonder how many others have made the same mistake?