As a dealer it can be just as bad "my mate down the pub/google/ brother in laws mothers' dog said" so just fit part, I don't want to pay diagnosis. Then they moan when it doesn't fix.

Just yesterday, a semi-auto Fusion has been diagnosed as needing a TCM relearn/update. The ecu has been reworked by ATP for another garage, after that the car won't start.

Actual fault, the selector shaft is seized. 10 minutes and the selectors work, car now starts. However the TCM has no comms, so what/who's to blame. Owner says he's not paying us to diagnose, but doesn't want to pay us for getting running either, as we haven't fixed the transmission fault!

Guess he won't be getting his car back then....