1990 GT Passenger Window stuck open

So now my window is stuck down, & I can't drive the car. The window stops working off and on, completely intermittent. When it won't open or close, all you hear is clicking in the Control Unit canister, under the driver seat. I opened the canister, and see nothing out of the ordinary. I just ordered a new Window Switch from 928Intl and installed it, but no change. I have never had the door panel off. I read about motor potential issues, but question how that could be intermittent. I suspect that Control Unit canister, under the seat. Anyone have any ideas on where to go from here? I have spent hours looking for a schematic of that Control Unit (928 618 240 00), but cannot find one. I could sure use some help on this one.

(I think this one will be my final straw. Believe I will drive it up to Petite le Mans at Road Atlanta this month, & put a For Sale sign in the window. A real shame, since it is an almost pristine original Baltic Blue Metallic GT 5-Speed, and a blast to drive.)

First thing Id look for is power to the switch then power at the window motor with the door panel off.
Double check fuse #31 and relays first.

Wiring diagram is on WSM 97-345

malcolm;12096 wrote: Double check fuse #31 and relays first.

Check here first. Ensure you have a good connection. There may be some corrosion at the fuse creating your intermittent operation.

He says it is clicking (the control unit) so he has power to the switch...

Kent, how long have you owned it? Remember these are OLD CARS man. They are going to have some issues. Wait till your cab top quits working...this window thing will look like and BE small potato's by comparison! I have seen that with Boxsters and 911 Cabs now... CHAAAA-CHING!!! '90 GT's are pretty mean 928's too, so if you do sell it someone will get a heck of a car for sure!

pcar928fan;12103 wrote: He says it is clicking (the control unit) so he has power to the switch...

Perhaps...take a DVM and check for correct voltage at all locations (switch, controller and window motor) to narrow the fault then tshoot further starting with the fuse and its position on the CE.

After the voltage test check continuity of wires to where the issue is........broken wire?

If confidence is high you could use a seperate 12v source on the motor to see if it runs.

Another issue could be high impedance (resistance) of a component.

Lots to check with a simple DVM.

Taking the door panels off are a breeze. Just take care to be sure that you have *all* of the hardware removed before you try to take it off. It doesn't take much to break the plastic support for the interior handle & parcel compartment. I believe there are 3 10mm bolts in total IIRC. Two inside the parcel compartment and one just inside of the cut out for the driver air vents. Be sure to get all of these 10mm bolts along with the handful of Phillips head screws and you're good to go. If you have a battery charger you can use the leads of the charger to apply direct power to the motor. If it rolls up, you can then drive the car and rule out the motor as well. That would make a nice head start toward your diagnostic work as well as get you back on the road.