My can can only reverse when I unplug the gear brain box but can drive with the brain box fixed
Check for shorted or corroded wiring to the transmission control unit. Is water leaking jnto it?
Yes the wire is very wet and the brain box is very hot when engine is switched on
well if its wet your giving the water a open invitation to spark all over the place which will likely short out your computer tcu (transmission control unit) take it out let it dry then reseal the box and make sure the cables are not wet and try it out again.
Looking for a Used Passat in your area?
CarGurus has 408 nationwide Passat listings starting at $2,000.
Search Volkswagen Passat Questions
Volkswagen Passat Experts