Question about 1984 Mercedes-Benz Mercedes Benz 300 Class
Tachomenter on my 1984 300D Turbo Diesel does not work. Thought it was the RPM sensor mounted on top of the flywheel housing so replaced it. Guess that wasnt it. Discovered that there was no continuity in one of the two wires between the plug in connection (to the RPM sensor) under the hood and the other end that puggs into the back of the Tachometer. Is there a switch or amplifyer, or some connection that could be out? if so where is it located?
You can also poke around on places like eBay, or look in a junkyard for this part. Mercedes calls it a Tachometer Amplifier. Unfortunately, they are know weak points on these cars. I'd recommend resoldering the connections, but the internals of this part are potted in silicone, making it VERY hard to get at the electronic components inside. Your best bet is to just find a replacement for that part under the screw-on cap. My 1979 300SD has the same part with the same problem, alas.
Posted on May 31, 2009
Hello, I can probably solve your problem but I don't know how I would get paid for it. I haven't seen this pop up under Premium Service on my end. Anyway, listen up. You probably have an earlier 1984 300D which has a TDC cap that controls the tach. It's located on the left fender apron about midway and has a screw-on black cap about 1 1/4" wide. If you unscrew it and pull up, it will come out and on the back side you should see about 3-5 pins This is the TDC cap and the most likely cause of the problem. Later 1984's and 1985 got the signal from the frt crank sensor.
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Posted on Feb 12, 2009
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Posted on Jan 02, 2017
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