Broke multi-pin instrument cluster connector - cluster now messed up - w123 - PeachParts Mercedes-Benz Forum

Zacharias · #1 11-01-2014, 07:14 PM

Finished replacing my ignition lock assembly today. That went great, what happened next, not so much.

It took me two tries to figure out the order to connect the cluster connections back up. (Big hands and fingers issues.) The only way I could do it was to push the multipin connector on last... and somehow I broke the alignment/guide piece off it.

I have not been able to find the right position to reinstall it. Any position where it wants to go on, the gauges and warning lights are all messed up. And there is never a preglow light.

I did try gluing that tab back on, but I am working outside in fall temps and the glue didn't set up properly and the piece broke off again. I have glued it again and will wait overnight.

Any tips on how to deal with this would be appreciated. What worries me is that I could swear I got it on properly aligned, twice, and while the gauges seemed okay and I had idiot lights, there was no preglow light AND the seat belt warning buzzer and light kept cycling on and off.

vtmbz · #2 11-01-2014, 08:41 PM

Wait til tomorrow-- I have an 85 w201 that might have the same plug-- Ill cut it out if so and send it to you.

Zacharias · #3 11-01-2014, 08:55 PM

I really appreciate the offer, vtmbz, but if that is the only way out I have a parts car here I can pull one off. Even where you are, it will take 5 days for it to get to me by mail....

I am mainly freaked out about the cluster electrics behaviour. I really think I had it correctly lined up twice and everything was still fubar....

ROLLGUY · #4 11-02-2014, 12:01 AM

I had the same problem on one that I did. I got the rotation correct by putting a mark 90 degrees from the flat spot on both the wiring plug and the cluster. It was then easy to line up both marks. It was a little hard on the plug with the center part broken off, so I also used the blank holes and gap in the circle of pins as a reference.

300dOwner · #5 11-02-2014, 07:15 AM

I broke mine too some time ago.

Here's the pinout

15-Pin Connector 84 300D Turbo

believe it should be the same.

The instrument panel board is numbered as well as the plug. Once you get it lined up make reference marks to align the two parts. I used white nail polish (wife still hasn't realized it's now in my tool box

)

Once you've got it marked, I found it's a bunch easier to see the marks by looking through the windshield from outside the car when reassembling.

vtmbz · #6 11-02-2014, 07:15 AM

I know all about trans border shopping-- the offer stands-- in a pinch I could drive over the border and mail it from Stanstead on Monday.

Zacharias · #7 11-02-2014, 10:07 AM

Appreciate all the help, guys.

One thing I find odd is that the diagrams don't seem show the blank receptacle opening. Maybe I haven't had enough coffee yet.

Here is my problem: the wiring harness for that plug is so damn short that once it is plugged in, there is virtually no manouever room to do the speedo cable or the oil pressure line. And I find that for both of those you need working room to get the threads started.

So it basically this multipin has to be the last plug that goes in, which means I am working by feel. So I have to have that aligning tab in place.

If anyone has a way around this, please let me know.

VT220D · #8 11-02-2014, 10:24 AM

Since you were able to get idiot lights and gauges you had the plug aligned correctly at one point.

The preglow system and the seat belt warning buzzer problem is likely related to the ignition switch replacement. The two work together. For instance, in my 240D, the seat belt buzzer will go off for the duration of the glow cycle if the belt isn't buckled.

If you replaced the ignition switch with the battery connected you may have shorted a pin and blown a fuse.

Either way I'd replace that connector - it's in bad shape. The cluster has some diodes in it that could be damaged and gauges can be destroyed. You can replace the shell without splicing by separating the halves. When you do be sure to press the harness into the connector. Otherwise once the connector is separated it will fall right off leaving you looking at wires and pins. While holding the connector on take careful note of the pin locations. Make a diagram ahead of time and fill in the colors. A helper is recommended. If you have a problem I can look at one of mine and give you the pinout.

ROLLGUY · #9 11-02-2014, 10:24 AM

Quote:

Originally Posted by Zacharias

Appreciate all the help, guys.

One thing I find odd is that the diagrams don't seem show the blank receptacle opening. Maybe I haven't had enough coffee yet.

Here is my problem: the wiring harness for that plug is so damn short that once it is plugged in, there is virtually no manouever room to do the speedo cable or the oil pressure line. And I find that for both of those you need working room to get the threads started.

So it basically this multipin has to be the last plug that goes in, which means I am working by feel. So I have to have that aligning tab in place.

If anyone has a way around this, please let me know.

On practically every one I have done, I have plugged in the multipin connector first, and worked my way to the right. There is slack in the wiring if you gently pull on it to find it's closest attachment point. Once you have enough length in the wiring, it is easy to see where the connector lines up after marks are made (cluster with left side out, right side in). I usually do the oil pressure line next, and then the rest of the wires, doing the speedo cable last. There is a bracket down between the steering box and the oil filter stand that has a plastic clamp that holds the speedo cable. If you remove the clamp from the bracket, it allows the cable to follow the contour of the firewall and gives more length inside to easily get a hand in to hook up the cable last (cluster with left side in, right side out)....Rich

VT220D · #10 11-02-2014, 10:38 AM

Quote:

Originally Posted by Zacharias

Appreciate all the help, guys.

One thing I find odd is that the diagrams don't seem show the blank receptacle opening. Maybe I haven't had enough coffee yet.

Here is my problem: the wiring harness for that plug is so damn short that once it is plugged in, there is virtually no manouever room to do the speedo cable or the oil pressure line. And I find that for both of those you need working room to get the threads started.

So it basically this multipin has to be the last plug that goes in, which means I am working by feel. So I have to have that aligning tab in place.

If anyone has a way around this, please let me know.

Paint a line on the connector and the cluster to show correct alignment and use an inspection mirror to check your alignment before reassembly.

I know what you mean about how tight the speedo cable is but I do the speedo last. I do the connector and oil line first then tilt the left side of the cluster slightly into the opening to get the speedo cable. Basically I'm installing everything from the right side of the cluster by laying across the driver's seat. It's tight but the left side tilt in lets me get it from the right. I use both hands and I have to start it with my fingertips I just did it this way two days ago after trying some LED bulbs.

Graham · #11 11-02-2014, 11:25 AM

Quote:

Originally Posted by Zacharias

The only way I could do it was to push the multipin connector on last... and somehow I broke the alignment/guide piece off it.

I have not been able to find the right position to reinstall it. Any position where it wants to go on, the gauges and warning lights are all messed up. And there is never a preglow light.

I have had the cluster in and out of my 85 300D many many times, I should remember how I do it, but somehow I don't.

Perhaps you can pull some extra slack on the harness, speedo and oil lines? Just a little might help.

Presumably you are doing this before you push the cluster back in place. I do seem to recall reaching in to back to push the plug on. And perhaps you are right that I would start with it close to correct, but then let the alignment tab help at the end. Is that whole center pin (with the flat on one side of locating pin) missing? If so, perhaps drilling a small hole through and inserting a small bolt or pin before glueing may be stronger?

This pic from a post by Funola shows the location of pins with reference to that flat:

Zacharias · #12 11-02-2014, 11:46 AM

I really appreciate all the input.

Unfortunately, I read all the latest input after I went outside and fought with it for 45 minutes....

Got it back together, aligned, once. Tested everything, all gauges and lights good with key on. Came off when I slid the cluster back into place. GRRRRRRRRRRRR.

Got it back in a second time, everything works, now suddenly glow stopped working (no light and no actual relay action).

I think I may have an unrelated problem there as I suspect the preglow relay stuck on at some point (battery suddenly drained).

What a fun weekend

Zacharias · #13 11-02-2014, 12:07 PM

Zap-charged the battery and now everything seems fine. Odd that the battery still had enough juice to groan over the engine a few times, but the glow light never illuminated at all.

Installed a charging system monitor into the cigarette lighter to see if the preglow relay is sticking on intermittently (this happened with a previous one).

Am also considering taking this battery back to Wallymart for an exchange.

The cluster is still not seated properly, protruding just slightly, but I am not going to mess with it any more right now. The current temps are not making things easier when working with plastic and wiring.

I guess I will live with it until spring, at which time I will attack it on a weekend when I have a second car available. And I will take all the advice into account on freeing up some slack on the wiring bundle and speedo cable.

Thanks everyone.

vtmbz · #14 11-03-2014, 12:28 PM

When working on wiring this time of year, I spray everything down with a hair dryer first (carefully) to get things nice and bendy.