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:
SERVICE BRAKE ASSIST
This message displays if there is a
problem with the brake system.
The brake system warning light and
the antilock brake system (ABS)
warning light may also display on
the instrument panel cl ...
General Towing Information
Only use towing equipment that has been designed for the vehicle.
Contact your dealer or trailering dealer for assistance with preparing the
vehicle for towing a trailer.
See the following trai ...
Roadside Service
(U.S. and Canada)
U.S.: 1-800-224-1400
Canada: 1-800-882-1112.
Text Telephone (TTY) Users
(U.S. Only): 1-888-889-2438.
Service is available 24 hours a day,
365 days a year. ...