w124 cluster acting up - PeachParts Mercedes-Benz Forum

JordaanDMC-12 · #1 12-12-2014, 05:39 PM

Hey all,

I'm wrapping up the heated seat install on my w124 and it required the removal of my instrument cluster, I've had this problem before but was able to get it to work and just didn't touch it.

What it's doing is I plug the round connector in on the back and the temp pegs all the way to the top and the fuel gauge pegs full and sometimes the a/c blower will come on, or I can put the blower motor on but it won't turn off until I move the cluster around

What's weird is that if I'm moving the cluster into position slowly I hit the spot where it works fine, but if I put the a/c blower on and the fuel needle jumps a little forward. When this happened to me before, it burned out my fuel gauge, had to go to the junkyard and get a replacement and unfortunately that's what happened to me today, it burned out one of my gauges.

If i move it into place slowly it'll jump to where it should but move it an inch and it goes haywire again. I tried looking for a short or exposed wire and I didn't see anything out of the ordinary. Is the cluster itself bad? Really irritating because all I had to do to wrap up this job was put everything back in, and now the cluster wants to act up again, delaying me from finishing

Any thoughts?

JimFreeh · #2 12-13-2014, 05:55 PM

Quote:

Originally Posted by JordaanDMC-12

What it's doing is I plug the round connector in on the back and the temp pegs all the way to the top and the fuel gauge pegs full and sometimes the a/c blower will come on, or I can put the blower motor on but it won't turn off until I move the cluster around

and now the cluster wants to act up again, delaying me from finishing

Any thoughts?

The round plug has an index tab to make sure the correct connections have been made.

I've had a couple of W124s where the tab is broken, or the locator slot is broken and you can attach the round plug out of sequence with the intended connections.

Amazing what can happen when you get the wrong input to a circuit....

Jim

JamesDean · #3 12-13-2014, 09:03 PM

I would have to agree with Jim. Check that connector. I broke the one on my 300D, luckily I had some super glue handy and put it back.

Either that or you have a grounding issue. I would plug in the connector(s) and check to see if you have a ground present at those screws on the back of the oil/fuel/temp pod.

If you are interested I do work on clusters and would be happy to test/evaluate things if you run out of items to check. Drop me an email and we can talk further.

JordaanDMC-12 · #4 12-27-2014, 03:00 PM

Thank you for the response guys, been a little hectic at work due to the holidays so I haven't been able to work on the car at all, she's just been sitting there.. dead.

That small piece on the connector that you mentioned is in fact broken, which is what has given me all this trouble I believe. I have to go to the yard and pull another gas/oil/temp gauge and hopefully I can get it to function. Wen I went to start the car because it's been sitting, I now noticed that the windows will not roll down and the sunroof won't do anything

Did a relay just go out, fuses seemed to be okay...

JamesDean, thanks I'll send you a PM

oldtrucker · #5 12-31-2014, 03:16 PM

Hi and happy new year,
seems to me a wiring problems.

You are talking about the 91 300E?

Sometimes, corrosion is your worst enemy. Also, as mentioned before, make sure the plug is correctly plugged in. Whenever I get into an area that can not easily accessed, I use some dielectric grease and put a small amount to the contact pins.
Another big problem, could be a bad return e.g. referred to as chassis ground. Unfortunately some of them may be located in a quite different place.
There are common points on the wheel well (bunsh of brown wires). It may make sense to undo them, clean the ring terminals and give em a bit of the dielectric grease. Then reassemble and see.
When gauges go haywire, it is usually related to a bad grounding system. There maybe a current needed but due to a higher resistance on the return, cannot be achieved. The result is "Jumping Jack Flash".

JordaanDMC-12 · #6 01-02-2015, 03:06 AM

Quote:

Originally Posted by oldtrucker

Hi and happy new year,
seems to me a wiring problems.

You are talking about the 91 300E?

Sometimes, corrosion is your worst enemy. Also, as mentioned before, make sure the plug is correctly plugged in. Whenever I get into an area that can not easily accessed, I use some dielectric grease and put a small amount to the contact pins.
Another big problem, could be a bad return e.g. referred to as chassis ground. Unfortunately some of them may be located in a quite different place.
There are common points on the wheel well (bunsh of brown wires). It may make sense to undo them, clean the ring terminals and give em a bit of the dielectric grease. Then reassemble and see.
When gauges go haywire, it is usually related to a bad grounding system. There maybe a current needed but due to a higher resistance on the return, cannot be achieved. The result is "Jumping Jack Flash".

Thanks for the reply!

Yes this is with my 300E, the tab the places the round connector on the back had broken off three or so years ago and every time I took out the cluster I always had problems putting it back in because of this, when I went to the junkyard to pull yet another fuel, temp and oil gauge I saw the plug with the cap from the donor car and saw that it was a clip and would come off. I decided to take the cover with the tab off and just put it on mine. I got a diagram off this forum for which wires went to which numbered port and it took me 8 minutes to plug them in, popped my new cap with tab in and I was good to go, no more guessing which way it plugs into and no more burning out gauges!!

However when that was finally in correctly, the gauges were still acting funny, the temp gauge would slowly peg and the fuel gauge would jump around but only when I put the car in a different gear; drive, reverse, neutral ect.. it was really strange. What was scary is that during my heated seat install I messed with a lot of wiring, having to move wires around and I started to think I maybe shorted something or something cracked? I decided to check a ground connection behind the cluster that I had to unscrew and add another ground for the memory seats from the donor car, it was hard to see, so I stuck my camera in there and low and behold found my problem. When I added the new grounding wire for the memory seats, I must have missed this one and it went astray and I just screwed it back in thinking everything was good to go. I put the stray ground back on and my cluster issues ceased to exist, which was a HUGE sigh of relief!

thank you for all your input on this, turns out it was something everyone on this thread said it probably was, a ground. It's amazing what can happen with a ground that's not properly seated!