W123 Mercedes Benz 300D Tachometer

This procedure will be performed on a 1982 Mercedes 300D w123. Tachometer on this car is not working. While there are a lot of other components that might cause this I am going to try something that is simple and we might get lucky .

There is a junction connection located on the left side of engine bay, right by the fender. Usually this connection becomes lose and does not make good contact.

Unscrew the cap.

Remove the connector from inside the cap, just pull it out.

Now, we need some kind of spacer between the cap and the plug inside. It can be done with almost anything,paper,cardboard, foam. In my case i used a piece of hard foam 2-3mm thick.

Put the spacer inside the cap and push the connector in.

Screw the connector in place. There we go,it’s working. I hope you get lucky too.

Comments (11)


  1. Cigars says:

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  2. Top Gear Streaming says:

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  4. andy says:

    Thanks for the tips.It did work for my 1982 MB 300TD. Any Ideas for oil leak?

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  6. TachGauges says:

    Nice tip. Add it to the collection of very nice tips.

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  8. Russ says:

    Holy crap! That was way to easy of a fix! Thanks for the write up!

  9. Leon says:

    Thank you. I did not know it was such and easy fix. I thought I may have to remove the dash or deal with the tach amp. On my car, I just sprayed contact cleaner on both the male and female connectors because the screw in cover won’t separate from plug

  10. George says:

    Holy Sh!t…it worked! I’ve been going without the tach for 6 months and dreaded having to take the dash apart. Thanks for the quick fix.

  11. Tom says:

    Just tried this on my ’83 300D – took 2 quarters and works like a charm!

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