Head Lights grinding.
The motors actually turn off based on an amp load when the lights shut off, kind of like a circuit breaker that pops when the lights shut down and the motor tries to turn past the stop..
The problem is bad design on Pontiac. They made the gear out of plastic. Over time the gear wears a little and then it just continues to jump the gear. Luckily after a little time it shuts off. Really annoying.
So 4 solutions.
Solution 1: The motor only strips about 1/2 the gear. So, You can disassemble it somewhat and get to the gear - - and turn the gears 180 deg. Then you get about another year or two before it wears out again. Its also a bit tricky to line up perfectly so you might end up going too far and it makes noise when you open them instead of close...
Solution 2: Disassemble - remove the gear - and find an aluminum gear and replace it. (or steel or another plastic.. I'd suggest if you go this far - get a metal gear) (it can be soft, anything better than plastic). - You can even 3d print a gear if you want - I'd impregnate some ball bearings or such into the gear teeth to prevent failure again.
Solution 3: - you can buy the motor kit from auto parts store - its about $140. Replace the whole motor unit. pretty simple but pricy - Sorry, Not sure if replacement motor has good gears in it or not ???? (I doubt it)..
Solution 4: - run the motor wire into the car - add a switch - then when you turn the light on / off - flip the switch to kill the power....
In my opinion - this should have been a recall.