Thread: Monte Carlo sunroof

One of the guys I work with has an '01 Monte Carlo he's thinking about junking. The sunroof assembly on my '99 GP sedan doesn't function very well so I was wondering does any one know if the two assemblies are interchangeable at all? I'm wanting to snag the assembly if they are. All I know is that it slides over the roof like the GP's

I wouldn't be surprised if they interchange, but you might be able to call the dealer and compare the part numbers to see if they interchange. Also, I've had a bit of experience repairing the sunroofs on these cars, so if you need help, I'll try my best!

Here's where I'm at. A little over 2 years ago I went to close my sunroof and it got stuck about 2/3 of the way upon sliding forward to the closed position. I eventually did get it closed all the way but now every time I try to open it tries to just slide the glass back instead of to the upwards position first. I have to push the glass gently with one hand along with pushing the open button to get it to the popped up position. I don't dare try to open it all the way as I am afraid of it getting stuck open again. It will sometimes blow itself shut if I have it open while driving on the highway.

I was told I need a new motor. Apparently halfway through '99 they changed the sunroof motor to a slightly different design and they aren't interchangeable unless I change the whole assembly. I have the earlier of the two designs with the red tabs on the motor which is relatively hard to find. It's not the end of the world but it would be nice to have a properly functioning sunroof again.

That's actually a new one for me! I have the "newer" design if I'm not mistaken, but I'm assuming construction is similar. I've never seen one mechanically be bad, it's usually the gears break. I think what you're experiencing is the sunroof doesn't know exactly what position it's in. Unfortunately these sunroofs are actually quite crude. It uses a bit of mechanical circuitry in the gear mechanism to tell the controller what position it's in. When the gears wear or skip some teeth, it'll stop before it reaches open or won't shut all the way. Unfortunately they made these gears from plastic. A new motor won't fix it unless it's the motor's teeth that are stripped. Basically, you need to drop the headliner to access everything. In gm's infinite wisdom though, you can't get to the gear box except from the upper side of the sunroof assembly. What I've done to avoid removing it completely is to remove all but the rear screws and loosen those and use something to prop the assembly on. It'll drop enough to reach the screws to remove the box. If you're lucky and the motor gears are stripped, you don't have to do this, just replace. Tricky part is the position. The roof won't move manually without the motor removed. So before all of this, open the sunroof as far as it'll go, then remove motor, manually open it the rest of the way, and re- install the motor. Lubricate and clean the tracks with silicone lubricant and test. Should be all good!

I greatly appreciate your knowledge. I definitely think the issue is with those plastic gears you mentioned stripping out causing the timing to be off.

How big of a job would it be to swap in another complete assembly? I can't imagine it being that much more involving than the procedure you mentioned or am I wrong?

You are correct. Once the headliner is down. It's six 10mm bolts if I remember correctly and two electrical connectors. Not bad at all.

Good that seems simple enough...at least with a 2nd pair of hands. Thanks for your help!