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I Have a W204 C200 CDI. Drove the car most of the day running errands, the car was fine, no issues. Last stop before getting Home, the car would not start. At first I thought it was the starter, but when I scanned it, I got a U0101 code (Lost Communication with TCM) multiple resets, but the car still won't start. I've also checked all the fuses and all seems ok. Is there any other way to reset the TCM and where is it located?
Im not sure the U0101 is going to tell you much. What type of scanner was used, a Mercedes specific scanner?
By not starting im assuming you mean you turn the key and nothing? Have you checked battery voltage using a multimeter? Ive read bad battery can cause the U0101.
Double check fuse #7 which I believe is the starter.
Could be a battery issue, or starter issue. I would say fuel pump but you say its not even turning over?
Both fuse boxes checked, all seems okay including fuse #7. Key turned to the on position and everything goes on as per normal except for the gear indicator, that shows all the gears (P, R, N, D) but does not highlight what gear the car is in and thus when turning the key to start, nothing happens.
TCM codes can be triggered by low voltage. Check your battery and alternator. Less than 11.7v engine off and 13.7v engine on, and you have a fault. That will easily trigger a fault code as many of these modules react to even a small drop in voltage.
Start there so as to at least rule that out. If youve had a flat battery or had to jump start it, that would be an obvious trigger for the code.
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