Hello everyone.

One of the problems with the vehicle has always been the one that every now and then the complete illumination of instruments and switches would disappear. When I pulled the instrument cluster out an inch the lights would go on again. Pushing the panel back would sometimes result in lights going out again. Sometimes not. I checked the resistor (dimmer), it was OK. This has been the case for a few years - after fiddling with the instrument cluster lights would be back and I couldn't be bothered taking everything apart searching for the causer of all of this.

Once the lights disappeared and nothing helped. I took the cluster out and apart and resoldered everything I saw inside it. Just to make sure. Lights would be on but pushing the cluster back would result in lights going off again. Eww! They would eventually go on.

Yesterday they went off completely and nothing ever helped. I made an appointment with the local MB dealer to have a look at that. Was worth the few $$$ I thought to get rid of that bug. I got an appointment for the forthcoming Wednesday 11th.

In the meantime I took the instrument cluster apart and VOILA! Owing to the fact that this time the lights wouldn't work permanently I was able to trace the faulty part. After all these years...

There are 2 prongs on which the dimming resistor sits, soldered through the circuitry board. One of the prongs seemed to be soldered perfectly but had no contact to next part of the circuitry board. I resoldered that very part. Since then I have light. I cancelled my MB appointment

Good for you! I cringe to think of what the parts-changers in the service dept. would have charged.

Tom

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CloudNine
'89 560SEC

Prolly the whole cluster

i was going to start this as a new subject. but since it's already here, here is my problem
1. my instument cluster lights does not work
2. my left signal light stays on (but does not blink)
3. when i signal to turn left the right instrument cluster signal light blinks.
4. my 2 front window switch lights not working
5. every now and then the lights for my heat buttom works but usually it not working
911 PLEASE HELP i can't see how fast i'm going at nite

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ez rider

dmon
When you say the insturment cluster blinks when you operate the right turn signal, and that your left signal does not blink, it is my impression that you have a failed ground in those lights. That is usually the cause of mysterious electrical gremlins of that sort.
With the other stuff will need to know the year and model of the car.

The device in question is called a DIMMER, a POTENTIOMETER, or a RHEOSTAT. By definition:

- A dimmer is a device used to vary the intensity of an electric light.

- A potentiometer is a 3-terminal resistor with an adjustable center terminal; used to adjust voltages.

- A rheostat is a continuously variable electrical resistor used to regulate current.

I prefer the term "RHEOSTAT" because it accurately describes both the operation and function of this device.



Whenever you have a problem such as intermittent or dim lighting with an instrument cluster illumination, this device should always be the FIRST THING to look at, especially on W126, W123 and W116 (and other older chassis). I did the same thing on my diesels, just like dieseldiehard.

Eric

Yup, I overlooked that miserable part. Worst thing in the MB inventory in my book. Have removed them from my fleet. Replaced with a wire with an end that slides over the posts left behind when that pos is removed. Simple repair.
I guess it is called a rheostat, but it will always be that pos to me.

3 of my 6 are soldered and I can't wait to do the others. Drove to work in the dark in my son's car today cuz the stupid thing is so picky. Can't wait to do the permanent job on that one as well.

Don

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