I have my friends car in the garage trying to figure his transmission problem i changed the trans. Put a used one in with 43 k kms same problem took it out for a test drive shifted fine the slippery road alarm sounded once and that light stayed on and it still shifted fine till i put it in park then goes into limp mode and when i put it in drive or reverse it kiks hard on the drivetrain code po138 po743 and c121c comes up. Anyone can pinpoint anything out of this ?

 

Ramout,

Sorry to hear the transmission replacement didn't fix your issue. The symptoms you're describing with regards to the traction control light and transmission behaviour are indicative of the codes being set.
This issue may be sensor related, or even an internal torque converter problem.
I'd hate to see another transmission replacement, a servicing dealer may be able to isolate this issue effectively.

 

Ty for the response we had brough the car to the dealer to get it checked and had told me the torque solenoid was the problem obviously wasnt after the tranny change it is now at a transmission specialty mecanic there was an issue with a vacum leak at the intake causing all other codes now only left with po743 telling us that there is a miss in the comunication between 2 of the onbard computers will post back when i get more input. Was also saying those transmissions are very solid and usually problem free. This would be mercedez transmission.

 

Well after all this the computer was the problem my friend had to buy another computer got it installed and reprogrammed at the dealer. They had checked all wiring and components first to make sure it wasn't the problem. At the end it cost him another 1100.00 $ and to find out that there was nothing wrong with the old transmission. I am not very impressed of the way the program works the only thing that this shows me that this vehicle is programmed to make sure you bring it in a shop for it would work good when i reset it and jump into limp mode once warmed up and make a change in gears i find that terrible. Y couldn't they just get the engine light tranny light abs light and esp light all come on just to say there is a problem and keep on shifting the same way as it was cold is beyond me. It wasn't my vehicle it was my friends and didnt really need a bill like this at this time of the year