See also:

Fast Idle System
If the vehicle has this feature it is available only with cruise control. The manual fast idle switch is operated using the cruise control buttons located on the left hand side of the steering wheel. ...

Safety System Check
Now and then, check that the safety belt reminder light, safety belts, buckles, latch plates, retractors, and anchorages are all working properly. Look for any other loose or damaged safety belt syst ...

Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if the v ...