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Nashvillecat 11-20-2010 08:34 PM

Instrument cluster

I took the instrument cluster out of my 83 D Turbo to install some LED lights, only one of the original bulbs was burning. When I began to put things together I found a problem with the main electrical connector, the round connector on the left of the cluster which must have a dozen or more wires leading to it. There was apparently a flat ended tab on the connector that slides into a slot in the cluster that ensures the plug is connected correctly to the instrument cluster. Well the tab is broken off, and there is no way to know how to attach the connector into the cluster correctly. All of the connectors are identical and spaced the same. Any suggestions? :eek:

cessna5354 11-20-2010 08:42 PM


My locating key is also broken, however you can look in to the socket and visually position the plug correctly. It can be a bit difficult working thru the dash, but you can do it.


charmalu 11-20-2010 08:58 PM

Wow, you are in a pickle. That centering piece is 1/2 round with a flat side to line it up correctly. with out that it`s like playing Russion Roulete. You have 15 possible ways for it to line up. the good news is, the cable won`t twist around, and has a set to it from the many years it has been bent to fit.

There is probably 3 or 4 pins eather side of proper lining up. I looked at one of my spare clusters and you are right, no identifying marks or numbers.

If I had this situation, I would hot foot it to PNP and cut off a plug with enough wire to see the color code. then if the plug will come apart (most mb connectors do) carefully open it up, and maybe the end piece will swap in.

I wouldn`t just try to randomly try different position to plug in the connector. could damage something in the cluster with 12v going to the wrong component.


vstech 11-20-2010 10:49 PM

I'll be posting pics of my harness in the morning. I"ve got lots of them taken apart.

Tpawlik 11-21-2010 09:05 AM

On my 87 300D each socket has a number printed on the face of the plug. Number 1 is at the 12 o'clock position. If you remove the cluster you can mark the 12 o'clock position on the cluster and then the plug to index the two properly. I know there isn't much wire to work with to accomplish this.
Good luck.

Yak 11-21-2010 01:03 PM

1 Attachment(s)
There are probably two issues: 1) knowing where they align, 2) getting them there in the limited space.

Look at pics, 48, 52 and 56 in the incredibly well documented DIY below. That seems to show that the there's an empty pin maybe a quarter clock-position off of the flat. That matches up very well with the attached pic.

You might be able to cover that unused socket with electrical tape to make it the new "key" that will align with the dash. But you're sort of betting that the tape will stick, you won't push it in, etc etc.

For a permanent fix, I'd suggest getting a new plug from a pick-n-pull. Digital photo of the wiring prior to disassembly would be wise - and notes on the wire colors on the donor and the repair plugs.

For a temp fix, and to make it easier to align, I'd pull the steering wheel. Put a paint-pen stripe on the unused socket on the plug, put a corresponding tick-mark on the gap on the cluster, line them up, and carefully test. Then re-assemble.

Alastair 11-21-2010 02:36 PM


This happened to me when I changed the inst. unit from a 280TE to the 300D type.

It was my own fault, the plug was pretty tight and I used a screwdriver under one side, the uneven pressure broke the half-moon spigot clean off level with the plug....:mad:

However, a little care and observation (On my particular panel/plug combo) suggested that the 'flat' on the outer rim of the plug sorta points to one of the dial-lamp holders.

--I shoved it in that position and Very quickly tried the Ign.

Thankfully all the normal lights/etc that you would expect with Ign. on came on as normal.....:)

Ive since painted a mark on the side of plug and the base of the pins/socket....;)

On my W123 Euro, the circle of pins is full. No gaps for reference....:(

Stevo 11-21-2010 03:29 PM

That happened to me and I didn't notice it till I plugged it in "one connection off" and toasted some things. After that I could plug it in and SEE the alignment would be correct, not a big deal.

Mark DiSilvestro 11-22-2010 01:06 AM

You may be able to examine the plug and actually see the outline of the broken/missing half-moon piece.
Then make a scratch-mark on the plug that lines-up with he flat of the missing piece.

Happy Motoring, Mark

charmalu 11-22-2010 02:37 AM

Note to self: Start cutting off plugs when Iam in PNP :rolleyes:.

I have used a screwdriver to loosen hard to remove plugs. I pry one side a little then the other to get it started, then wiggle it off. I never thought the plug would break, thought the fiber material on the rear of the gauge would crack first.

Nashvillecat 11-22-2010 10:36 PM

I don't think I broke the plug on the female connector, I am pretty sure it was broken in the past. I even took the cluster apart to see if I could identify the dummy plug. My car does not have a missing male plug and all are soldered in. The only thing I can see is that two of the plugs are not as shiny so one of these is probably the unused. I have probably fried something but of course can't tell without finding the correct connection. I may have to get another instrument cluster with the female plug attached and get the orientation that way.


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