Two things come to mind. First of all, GM has had a huge problem with front wheel bearings. They develop a little play which is completely normal, but it's enough to allow the signals to drop out for the anti-lock brake wheel speed sensors that are built in. The dealer's scrap metal bins are full of these bearings. They often cause problems in as little as 15,000 miles. You'll need a scanner capable of accessing the ABS Computer to read the stored diagnostic fault codes. It will also allow the mechanic to view the wheel speed data on a test drive. From that he can see which signal is being lost.
A second real common problem that also affects only GM cars is the generator. Due to its very poor design, they develop a lot of voltage spikes that can destroy the diodes and voltage regulator inside it, and those spikes adversely affect the many other computers on the car. It's common to go through four to six generators in the life of the car. To prevent the repeat failures, replace the perfectly good battery at the same time. As they age, they lose their ability to dampen and absorb those spikes.
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Wednesday, October 26th, 2011 AT 9:10 PM