I have 1990 f150 SC and the passengers side window only wants to go up when using passenger door switch I have checked out the motor it is fine triedchanging the switches around. The drivers window works great the control sw for the passenger side doesnt work in either direction from drivers door. I was told my truck doesnt have relays if anybody has information it would be greatly appreciated. Thanks...

 

It sounds like the driver's side switch is shorted out some where. You can use a muti meter to check the currnet at the switch, wire, motor, etc. to try to find where it is shorting.

Gotta love electrical problems... Good luck!

 

Drivers side switch is shot - replace it. Repair is possible only sometimes - but more technical. Actual switch inside may be beyond repair.