I had a similar problem, ended up replacing the motor and ECU (just one day I parked up in high then when I restarted the car was in low and wouldnt come out). Got a set of transistors to fit but then discovered a blown diode that I couldn't identify so to avoid risking blowing up the BECM I just got a secondhand transfer box ECU from fleabay.
As others have said, numerous revisions - Google is your friend for this one!
Good luck