i have a MY 02 270CDi ML with the 722.6 trans . I have replaced the trans with as low mileage used one (the original one had a catastrophic failure at 260,000 ) But i have since replace the contact plate three times ,the TCM three times and tested the solenoids which are all OK . But it refuses to go into 4th or 5th . Once it goes into 4th it goes straight into limp home mode,in 3rd gear so the touchtronic shift stops working . Last week I pulled the valve body out again replaced the contact plate,pilot bush etc with genuine mercedes parts instead of chicom knockoffs and still i get P2502..
Now the problem as it sits right now
the scanner (isoft) tells me I have no DTC's in another circuit but the TCM says i have code P2502 trans slipping or implausible gear... Thats OK, but without driving the vehicle etc , the scanner cannot remove the code. Is this normal or is the TCM fualty ...again ?

PS i have washed ,stripped cleaned all the wiring loom plus the other looms connected with it to remove all trace of the old trans lube.