I've read and followed several threads but even after cleaning the TCM circuit board (which looked fine) and the male/female plug (some corrosion and attempted to clean with electronics cleaner, fine brush and added DE gel) I'm still getting the Gearbox Fault alert. The car will start fine with no Code but after driving a few minutes with some hard shifting in gears 1, 2 and 3 the Gearbox Fault alert will appear and the car goes into limp mode. I do have a P0778 Code, Pressure Solenoid and P0101 Mass Air Flow. I may not have cleaned the male/female plug well enough though not sure how to clean the female portion of the plug other than a inserting a paper clip into the female portion and attempting to carefully "scrape" the connector. Any additional ideas or recommended cleaners for another go?

 

Replace the MAF, it's not too expensive, and try cleaning the Throttle Body and connector plug male/females. There is also a vent hose that runs parallel to the airbox tube that connects to the throttle body. Is that a newer ribbed one? The older ones split.

 

what code reader are you using you may not be getting all the codes from your geargox mine said gearbox fault but my reader did not pick them up when i took it to a gearbox shop they read lots of faults it could be your pressure solenoid or more