Tach keeps jumping in and out. Will sometimes work for days and then drop out for several.
Also tranny has started slipping at times and I was told there is no adjustment for the transmissions in this model, is this correct??
Also cruise control surges at times, works well others.

There is a relay that is located on the left wheelhouse assembly. I think it is called a TDC sensor. It has a wire that goes from the bottom of the relay to the harmonic balancer. I had the same problem and I replaced the part and the tach no longer jumped. You could try dropping some crazy glue into the metal prongs on the underside of the relay. Sometimes they get loose and you get this problem. In order to remove the relay, turn the black cover counterclockwise and unscrew it off the mounting base. You'll see what I'm referring to. As far as your tranny goes, you could try adjusting the transmission pressure by fine tuning the governor or modulating valves on the side of the transmission, but if you don't have any idea how to do it, then I would recommend you go to someone who does. Good luck.

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The tach transducer in the diagnostic socket is undoubtably the tach problem. Sometimes just removing it and reinstalling will correct the problem. Most times the unit needs replacement.

There isn't a transmission system in the world with more adjustments than your car. An expert here is worth his weight.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

After reading some posts last year about non, or erratically funtioning tachs., I decided to go for the butt in the can trick. Unscrew the cylindrical plastic piece, gently pry out its guts (in one piece of course), and then stick in either a cig. butt, or a styro peanut and put the whole sh'bang back together.
Hope this works
-Larry

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03/83 300D 184k
07/73 280 160k

Thanks for the info, for some reason your e-mail address alone would not come up so I am haveing to use this format. I think what you have given me for information will allow me to fix this particular problem, it is just annoying to me. Thanks again

quote:

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, RicOriginally posted by Mustafa Ahmed:
There is a relay that is located on the left wheelhouse assembly. I think it is called a TDC sensor. It has a wire that goes from the bottom of the relay to the harmonic balancer. I had the same problem and I replaced the part and the tach no longer jumped. You could try dropping some crazy glue into the metal prongs on the underside of the relay. Sometimes they get loose and you get this problem. In order to remove the relay, turn the black cover counterclockwise and unscrew it off the mounting base. You'll see what I'm referring to. As far as your tranny goes, you could try adjusting the transmission pressure by fine tuning the governor or modulating valves on the side of the transmission, but if you don't have any idea how to do it, then I would recommend you go to someone who does. Good luck.

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We had an 82 300D for many years and had several problems with the transmission slipping when it shifted from 2nd to 3rd or 3rd to 4th. Each time it was fixed by an adjustment.

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Chuck Taylor
Falls Church VA