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:
Tire Designations
Tire Size
The following is an example of a typical passenger vehicle tire size.
(A) Passenger (P—Metric) Tire:
The United States version of a metric tire sizing system.
The letter P as ...
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 ...
Contacting Roadside Assistance
Roadside Assistance services
are of no cost to you and available
24 hours a day, 365 days a year.
Costs are only incurred in situations
that exceed the limits of the
program, some of which ar ...