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:
Other ITBC-Related DIC Messages
In addition to displaying TRAILER GAIN and TRAILER OUTPUT through the DIC, trailer connection and ITBC system status are displayed on the DIC.
TRAILER CONNECTED: This message will be briefly displaye ...
Trailer Towing
If the vehicle has a diesel engine, see the Duramax diesel supplement for more information.
If the vehicle is a hybrid, see the hybrid supplement for more information.
Do not tow a trailer during br ...
Taillamps (Chassis Cab Models)
A. Backup Lamp
B. Stoplamp/Taillamp/Turn Signal Lamp
To replace one of these bulbs:
1. Remove the four screws.
2. Lift the lens off the lamp assembly.
3. Turn the old bulb counterclockwise and ...