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 
, and an Advisor can run a check.
See also:
Tire Sidewall Labeling
Useful information about a tire is molded into its sidewall.
The examples show a typical passenger vehicle tire and a compact spare tire sidewall.
Passenger (P-Metric) Tire Example
(A) Tire Size: ...
Vehicle Messages
Messages are displayed on the DIC to notify the driver that the status of the vehicle has changed and that some action may be needed by the driver to correct the condition.
Multiple messages may appe ...
Compass
The vehicle may have a compass in the Driver Information Center (DIC). ...