1986 Mercedes 300 SDL Instrument Cluster Plug Alignment
 

Good evening all

I have a 1986 Mercedes 300 SDL with 280,000 miles on it. I decided to pull the cluster to install a spare unit. My speedometer hasn't been working since I purchased the car. I installed the spare and there was no change to the speedometer.

My big question: How do you know the proper alignment for the round black plug that fits on the rear of the unit? I noticed that some of the dash lights were on that had not been on prior to install.

After removing the plug several times, I also notice that different variations of the turning of the plug and install would change which warning light, gas gauge, and etc. worked.

So now I am completely confused as to which is the proper alignment. HELP Someone....

Ron

I have seen this problem before and will try to explain the problem and a possible way around it. If you look at the instrument panel at the plug location you will see a hole in the center of the circle of pins. It will have a notch in the edge of the hole. This notch is a keyway to align the plug. Now look at the plug and you will see that the pin (about 1/4 in round) is broken off. Look very carefully and hopefully you will be able to see where the key was located on the missing pin. Mark the plug and socket to show the key location so you can align the plug correctly when you plug them together.
Did that make any sense?

Paul

Yes that did make perfect sense. I will take a look at it in the daylight and give it a try. Thanks for the help. I didnt didn't think I was the only one with this problem.

I also learned I may need to change the electrical pulevon the back of the ignition switch behing the tumbler. I've completed this repair and few time on my previous 123 model. Any tricks to doing it on the 126 model?

Paul, I totally appreciate your help.

My 84 is a generation 1 car and I believe the 86 generation 2 cars are different so maybe someone else can help on that one. I did have to change the steering lock on mine some time ago and it was quite involved if I remember correctly.

Sorry I can't help on that one. I may give you bad advice.

Paul

Thanks Paul

Paul

I looked at the hole and pins and could not find the notch you mentioned. Ideas anybody?

Ron

I'm sorry, it is not a round hole with a key, it is a D shaped hole that has 1 flat side. The pin on the plug would fit in the D shaped hole.

Paul

The center of my plug no longer has whatever was in the center.