My girlfriend has a basemodel 99 pontiac grand prix 4 door. The window stopped working some time ago. Now it has gotten to where it will slide open on its own. I am assuming that the motor is bad. Anything else it could be? Where is the best place to buy replacement parts?

Thanks
Charles

Do you hear the motor moving when you hit the button? Could be the internal cable is broke. Pull off the side door panel (combination of screws/clips. 2 main screws under interior door handle). You'll need to peel back the plastic watershield to see the regulator through holes in the door. Motor is held on by 3 screws. I think 1 is under the speaker. Regulator has 2 or 3 screws, can't remember exactly. You can buy the motor separately, if the regulator mechanism is ok.

Do you hear the motor moving when you hit the button? Could be the internal cable is broke. Pull off the side door panel (combination of screws/clips. 2 main screws under interior door handle). You'll need to peel back the plastic watershield to see the regulator through holes in the door. Motor is held on by 3 screws. I think 1 is under the speaker. Regulator has 2 or 3 screws, can't remember exactly. You can buy the motor separately, if the regulator mechanism is ok.
I do not here the motor moving at all. I guess I just need to take the door apart and see what is going on in there.
Where would be a good place to look for buying the motor and regulator?

I bought it at a local auto parts store. Call several. You'll find some variation in price. Think it was about $100. Can probably find them online for less, if you can stand to wait.

I got mine for 80 bucks off of eBay. Took about 45 mins to change it out. If the window is falling down, the cable is broken. You have to buy the entire motor to fix it. It will have the motor, the regulator and the cable all mounted on one bracket.

Thanks for that info. I figured it would all need to be replaced.