Benz s500 2002 Transmission control unit TCU repaired

Benz s500 2002, S500 symptoms and p0600 code

ECU looked good and dry and read that the 600 code could be for the tcu so i found the tcu and removed it and a ton of water poured out. So i thought it was cut and dry the tcu was bad. Found a good ebay seller that had one with the same exact part numbers so i bought it and installed it yesterday. Now the gear selection indicator works in the dash as well as the engine and abs light and all are gone. Thats all good and all but the trans still does not shift!!!! Still stuck in limp mode 2nd gear. Other thing i notice is the triptronic 1-5 thing does not work nor does the s/w switching.

Working solution advised by experienced tech:
You need to either take it to a MB dealer or find someone with a STAR diagnostic computer to reset it. Nothing else will work. It should be less than $200.

Since the car only goes about 40-50 max so I can’t really drive it to a dealer. The TCU has to be reset to let the transmission know that everything is back to normal. They are designed to go into limp mode in order to not cause further damage to the transmission.

To explain clearly, in your original inquiry you sated that when you opened the TCU “a ton of water poured out”. In addition to the TCU you might want to clean your reed valve to make sure it is clear of debris such as leaves, sand, dirt, etc. If that thing fills up it will cause you a multitude of problems including water leaking into the car (passenger side US version) and eventually screwing up all the electronics.

Now as far as the TCU is concerned:
The transmission has stored error codes. They have to be cleared and the new/used TCU has to be matched to your car. A typical Benz diagnostic tool will not be able to do this. It will take a STAR DIAG tool. Just tell them that you replaced your TCU and need to have the error codes reset so that the transmission will recognize that the problem has been fixed.

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