2000 S500 Transmission issue
I have a 2000 S500, I have owned it since new. Over its life, only regularly required maintenance has been done, with of course the wear and tear items replaced, battery, tires, rotors, brakes, oils filter etc.
it has 145,500 miles on it. The car has been a west coast car. In the past two months two problems have developed, is transmission which is very random in nature, and I have not been able to duplicate it in front of my mechanic, a Mercedes certified independent. On random days, the the transmission will not shift past second gear, and the shifter will not move up past neutral to park.
I have to pull the car over, shut it down, pull the key out, reinsert and start again, sometimes only once and sometimes several times upto 4-5 times. Then the car and it’s transmission works as iff nothing happened.
Any help or ideas will be welcome.
PS. The transmission while a sealed unit and the manual says lifetime oil, I had the oil drained several years ago, at about 80,000 miles, it has been driven an average of 7000 miles per year, as I have other cars that need to be driven.


This part of the post is puzzling. Are you saying that the shift lever won't move past NEUTRAL?
One possibility for the shift problem is transmission fluid in the Transmission Control Module. The electrical connector on the transmission sometimes develops a leak, and the leaking ATF wicks up inside the wire harness to the TCM. The TCM is a black plastic box the size of a pack of cigarettes, stuck down in the wire harnesses in the right front SAM. (Remember that right/left is always in relation to the seated operator.)
Get a spray can of brake/parts cleaner. Remove the SAM lid, and carefully examine all of the wire harnesses for any traces of oil. Pull and wiggle the oily harness to extract the TCM. Gently pry open the box, and (using eye protection) thoroughly clean the electronic board and components. Let dry, reassemble and reinstall. Let us know whether or not this helps.





