NEW TO FORUM NEED A QUESTION answered im desperate. i have a 2002, C230 compressor
the transmission want come out of 1st gear. i took it to the Mercedes dealer and the charged me for 2 hour of labor to tell me i have to change out the TCU to before the can farther troubleshoot it but there not sure if that the problem. my computer code read bad speed sensor. my Question is why do they say they have to program it to the car what dose that require and why is cant i just plug it to my car and remove the old one.

 

If the current TCU is giving out codes it sounds like it is working correctly. A "good" dealer should be able to recognize this. Get the code and google it. There will be lots of info to sift thru. A sharp tech should be able to get to the core problem with that info.
Parts departments don't like to take back high dollar electronic parts on a diagnostic guess. Sounds like they want you to take the risk. Certain problems can take out the new TCU if the tech made a mistake. Some TCU's also record the VIN of the vehicle as part of their master program. In some cases the TCU has to return to a rebuild center to have the vin erased. Keeps salvage yards from selling TCUs? Good luck.

 

you need a conductor plate most likely. its the electrical plate on top of the valve body, you probably have a bad speed sensor.
usually about gonna be about 500.00 at the delaer. depends.
trans control units can get trans fluid in them and fail too..does happen

 

I have 1989 mercedes benz 420sl great shape, but my speedometer stopped working could it b a fuse? I hate to get rid of it new belts, raditor brakes rotors alt. battery and tires,

 

that is cable driven sometimes it comes lose at the back of the cluster. could need a new speedo

 

OK just changed my conductor plate today, didn't see any speed sensor on it. but changed it anyway hoping this will fix the problem. my problem is that the transmission want shift out of 1st gear. while changing out the plate i seen some other part on top of the valve body and was wondering if any of them might be the problem.

1: valve solenoid. part # A1402770435
2: pressure control valve. part # A1402770535
3: lifting magnet part# A1402770398

should i have changed any of these out when i was change the conductor plate.

also my speed gauge don't work what would control that from not working, will this problem be related to my transmission problem. do any one know what need to be changed to fix it and what part number is it.

 

could need to clear codes. where did you get the new plate from?
did you install the transconnector corectly. correct fluid level.

 

no didn't clear codes, because i don't know how and was thinking if i replace part that they will automatically clear.
yes transconnector is connect correctly

how do i go by clearing codes?