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:
Engine Oil Pressure Light
WARNING
Do not keep driving if the oil pressure is low. The engine can become so hot
that it catches fire. Someone could be burned. Check the oil as soon as possible
and have the vehicle serviced ...
Online Owner Center
Manage your vehicle (U.S.) at gmc.com. Click on “Owners,” then “Manage My GMC/Owners Login.”
Information and services customized for your specific vehicle — all in one convenient place.
...
Automatic Dimming Mirror
If the vehicle has the automatic dimming mirror, the driver outside mirror automatically adjusts for the glare of the headlamps from behind.
This feature is controlled by the on and off setting on th ...