Hey,

I have an issue with my sunroof. It won't stay in the "closed" position. If it'* open and I press "close", it slides back forward but doesn't rise to be flush with the roof. Likewise, if it'* in "vent" and I close it, it just friction fits into the roof until I go over a bump or close a door or something, then it drops back down like it'* ready to slide open again. Currently I have it proped closed with a chunk of foam but I'm looking for a more.. proper solution. What part of the assembly is suppose to hold it closed? I haven't seen one that works so I'm not quite sure what I'm looking for. Nothing in the assembly looks out of place or broken to me.

Have you cleaned all the tracks that it slides on. Maybe something is blocking it from completing the close cycle. Also try cleaning the switch assembly with spay electric cleaner.The track will need to to be lubricated I assume, GM should be able to give you the correct lube.
Also maybe a bad ground circut. Nice loccking car mine is the same color but no sunroof.

Hey thanks. I love the green.. looks great on the older Bonnies.

I'm not sure it'* an obstruction or a switch issue, since it will go to the "close" position -it just won't stay there.

There was an obstruction a while ago ( bolt in the track) preventing the sunroof from opening, but I solved that. Maybe it damaged something else.

Its not an obstruction ill tell you now... mine has the same problem, well sorta... doesnt close all the way and from vent it just drops to completely open, but if i push it up to the flush close while holding the close button itll hold firm, just a pain when it rains and its not sealed perfectly...

not sure what the problem is, ive been thinking the motor just doesnt have the strenght anymore given the age and i know mine is original... but i really dont know what it is causing the problem.

There'* three parts to a sunroof that can have an issue. The track, which is the most common. The motor which works in conjunction with the track and the module.

I think the module is fine.. and the motor seems to move it through it'* full range of motion.. guess there'* something broken or not engaging in the track?

There is a gear on the motor for our sunroofs that drives the cables that open, close and tilt the glass. If the glass encounters an obstruction, it is easy for that gear to skip a few teeth. Once it does that, it loses its "home" position, and stops short or past the closed position. You have to play with the switch to get it to the right position. The fix is to drop the headliner to get access to drive motor, and reposition the gear to the home position. I had a trim shop do this for me, so I am not entirely certain what defines home position, but I think there is a mark on the gear you line up so something. If you are going to do this, let me know and I will check my FSM to see what it says on this.

The other thing that can happen to our sunroofs is the drive cables can get stripped, not at the motor end, but at the other end that drives the glass motion. My understanding is these drive cables used to be sold as seperate items, but not any more. If your cables strip to the point where it won't drive the glass, you have to buy a whole new sunroof assembly.

If anyone knows where you can buy the drive cables as seperate items, please let me know. Mine are still working, but they are worn and I use my sunroof sparingly because I don't want to strip the cables.

Hmm, thanks for the info. It could be the motor position.. although I just find that unlikely because the sunroof will go through all it'* ranges of motion -full open, closed, and vent- without issue. It just doesn't seem to "lock" in the closed position.

There is no secondary device (like a lock mechanism) that engages to hold the sunroof closed. It is just a stable position in the travel. If you are sliding it forward from the open position and it doesn't rise to the flush position, it is stopping just short of the home position. One more bit of travel would push it to where it needs to be.

My bet is on the gear position relative to the drive cables. You are probably only one or two teeth out of position.

By the way, one of the ways this can happen is if you over-travel your sunroof. When you hit the open button, the glass automatically moves to a preset open position. This position is determined by the rotational position of the drive gear. If you hit the button again, it will open another 1/2" or so. Problem is, now you are stopping the glass by taking it to the limits of its travel, and it is stopping against a hard point. This can cause the drive cables to skip a tooth or two on the motor gear. Just open the sunroof to the limit it is set to automatically open to. Don't open it that extra 1/2".

The other thing that can cause the drive cables to skip teeth on the gear is the crappy wind deflector that pops up from the front of the sunroof opening when you open the glass. The sole purpose of that deflector is to prevent that "drumming" noise you sometimes get when opening a window at highway speeds. I call them crappy because they break so easily. On my car, the deflector broke and when I shut the sunroof the glass jammed on the broken deflector and caused the drive cables to jump teeth.

I was working on a new vehicle interior design a few years back, and was dealing with the company that manufactures the sunroofs used on my Bonneville. One of their engineers showed all this to me on a cut-away mock up of a sunroof assembly.

Interesting. Sounds like my problem could definetly be a skipped gear then, considering when I got the car there was an obstruction in the track preventing it from opening. Any idea how to get at the drive mechanism?