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 vehicle is equipped with the Tire Pressure Monitoring System.
If a diagnostics check is needed between e-mails, push 
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Advisor can run a check.
See also:
Wheel Alignment and Tire Balance
The tires and wheels were aligned and balanced at the factory to provide the
longest tire life and best overall performance. Adjustments to wheel alignment and
tire balancing will not be necessary ...
Headlamp High/Low-Beam Changer
Push the turn signal/lane change lever away from you and release, to turn
the high beams on. To return to low beams, push the lever again or pull it
toward you and release.
This indicator lig ...
Automatic Transmission Shift Lock Control Function Check
WARNING
When you are doing this inspection, the vehicle could move suddenly. If the
vehicle moves, you or others could be injured.
1. Before starting this check, be sure there is enough room aro ...