So you have established that the switches are OK, the motor and mechanism is OK - therefore the problem must be in the wiring. The checks you have done with the wiring prove that the + side of things is working OK - it is quite happily switching the +12V from one wire to the other. And as the window will go up, we know that the earth is present on the other wire when the switch is in the up position. So, it must be that the motor is not being earthed when the switch is in the down position...jonkw wrote: T1 gives 12v when switch is pressed down
T3 Gives 12v when pressed up
T2 is blanked.
Sorry, after writing this I realise that I haven't actually suggested how to fix the problem - I would normally think that it is an internal break in the wiring between door and A pillar, but if that was the case I would only expect the problem to be with the passenger door switch on the driver's door. Hmmm, puzzling. I hope my ramblings have helped slightly, maybe with a fresh(er) brain in the morning I can be of more use...