When I first press the light switch, the doors will open sometimes. 1st time will work about 25% of the time. Once and a while the second time I try, it will open them. Other wise it won't work at all. Lights turn on but motors don't open the doors. If open, they will close properly every time. I checked the connections by the light motors, they seem to be making contact.

From reading other threads I see there is a module that controls them. How can I test it. Where is it located and does anyone have a part code. Does GM still sell them?

 

There are three parts to the system... The switch, the module, and the motors. Generally speaking the motors either run and don't move (worn bushings) or they don't run. The module is a couple relays and an electronic circuit that determines when the headlights are all the way up, all the way down, and when they should switch. The module is what usually fails.

GM made a couple different modules. They aren't all interchangeable, you need the right one that matches your car. It's easy to find out which ones will interchange with a Google search. I'm pretty sure GM doesn't have them anymore, but they would be around $300+ if they did. You're better off getting a good used one.

Before I replaced the module, I'd probably try another headlight switch. Mostly because the switch costs $15 and is easy to come by. The symptom of the headlights doing different things after you press the switch several times kind of points to the switch too. Generally when the module goes, you'll have one headlight or the other or both that will go up, but not down, or down but not up, etc.

 

When it works both go right up with no problem. I will check/replace the switch first.

 

I'm sure there is a troubleshooting chart in the GM service manual. It'd be worth the trouble to find a copy and run through it.

 

Thanks Drew! At $15, I just bought the switch and replaced it. They opened right away. I figured if it wasn't that, I would at least have a good spare.

 

Good deal, I'm glad it worked out for you. And now you can keep an eye out for chances to pick up a couple extra modules, just in case you need one in the future.

 

For future reference, Lon at TopDownSolutions sells refurbished headlight modules. Haven't checked in a while, but IIRC they were $65.