Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
My answer may not be exactly what you want to hear, but I will try to explain it. Assuming the sunroof drains were clogged and not pinched off, this would allow water to get into electronic modules and wiring that it was not originally intended to causing those parts to fail. The drains being clogged with debris would be a maintenance repair and not a defect. If the drain was pinched off from the factory and causing the clog this would be a warranty repair, but would have only been covered by the 4yr/50K mi bumper to bumper warranty on the car. Since the car is a 2008 model year the warranty ran out at 4 years from the start date which would be when the car was purchased new or when it reached 50,000 mi which ever came first. GM is only required to cover warranty repairs while the vehicle is still under warranty. After the warranty expires all repairs are the customers responsibility.
The only way to test to see if the drains are clogged is to periodically open the sunroof and slowly pour a small amount of water into the sunroof track housing area at each corner of the sunroof opening between the track and the edge of the roof. If the drain is clear and free of debris the water will exit the drain and you will see the water pooling on the ground near each of the wheels. If the water remains in the sunroof track housing and is not seen coming out the underside of the car, then one or more of the drains are clogged.
You are welcome. Let me know if I can be of any other assistance.