Are we talking about a cruise control problem, a rough running engine, a traction control light, or are all these things related?
For the cruise control kicking out only when going downhill, suspect the brake light switch is misadjusted.
For the traction control light, the ABS light should be turning on too. GM has been having a huge problem with front wheel bearings and their built-in wheel speed sensors in as little as 15,000 miles. The GM dealer's scrap metal bins are full of these bearings.
With GM Engine Computers you also have to read "pending" codes to get a clue to the cause of rough running. Those indicate things the computer has noticed but not set a fault code for yet.
GM also has a problem with their generators developing large voltage spikes. They can destroy the internal diodes and voltage regulator and can induce voltage spikes into adjacent wires in the harness. If a spike gets induced into a sensor wire, the Engine Computer can be confused and will try to act on that incorrect information. You can identify that by unplugging the small connector near the back of the generator while the problem is occurring. If voltage spikes are the cause of rough running, it will clear up when the generator is unplugged.
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Thursday, April 19th, 2012 AT 6:05 PM