A small wiring/power window problem.

[mcninetyone]

The car is a 94 GM.
The problem is in the left rear power window.
The main switch in the drivers door will move it down but not up.
And sometimes the drivers door switch doesn't work at all on that window.
The switch on the rear door will move it down every time, no hesitation, but not up.
The regulator is not broken and in great condition.
The motor is also working perfectly as it should, plastic bushings replaced.
Out of the door and in my hand the motor only goes one way.
Tried a second motor, it only goes one way too.
So whats the problem?
I'm guessing the drivers door main switch?

The other three windows work just fine, up and down.
No wiring has been cut, spliced or butchered in anyway.

[jaywish]

When you say in your hand, do you mean still connected to the switch or powered manually by you direct to a battery with some alligator clips or the like?

Can you swap the 2 rear switches side to side on that car?

[sly]

I'll pull up the wiring diagram when I get home from work and see if I can figure out what's up.

[mcninetyone]

Jay, "in my hand" means still plugged into the car wiring harness but with the motor in my hand and no longer attached to the regulator.
I could swap the switch, and might do that just to see what happens.

sly, thanks for looking, anything you can come up with will be appreciated.

[gadget73]

problem is, both switches need to be good in order for the motor to work correctly. I'm betting one of the switches has a fouled normally closed contact but without knowing how they function internally I couldn't guess at it enough to tell you how to ohm it out. Box switches you can open up and clean inside, don't know about more modern ones. Suspicion makes me say its probably the driver's door switch since that one has likely been used more times but no guarantee on that.

If the two rear door switches are the same, try swapping them to see if the problem moves. If no change, that points even more towards the driver's switch.

[sly]

if the motor works at all, the rear switch pass-through is working. If up is not working on both switches... then the ground at the driver door switch is bad on that switch for up. There should be a ground bus in the switch matrix that goes between all 4 switches. The way these things work is by grounding and powering the 2 wires. The switch both powers one wire and grounds the other to get the motor to turn. It does this by breaking the ground of one to apply power and making the ground of the other. It really is a simple setup, but the contacts in the driver door are prone to corrosion. I'm not sure it can be disassembled and cleaned very easily (I think it's assembled with pressed rivets) but it might be doable.

To test this idea, pull the motor, measure resistance to ground on the car harness. Might need someone to press up on the driver switch as you hold one lead in the motor harness and the other on a good body ground point. You should see less than 1 ohm (at least less than 5 on an oxidized spot). If one of the wires is open when the switch is in the up position (should be the red/yellow one) then has power in the down position, then that's your problem.

[mcninetyone]

Thanks for all the help! Because of work I'll have to wait till this weekend to go at this car again.
When I finally find and answer I'll let everyone know what it was.

[mcninetyone]

The problem ended up being in the drivers door main switch. I replaced it and now everything works great again!

[sly]

Figured as much. Glad it's fixed.