See also:

Muting a Call
To Mute a Call Turn or press the MENU/SELECT knob and select Mute Call. To Cancel Mute Turn or press the MENU/SELECT knob and select Mute Call. ...

Competitive Driving Mode
To select this optional handling mode, press the TCS/StabiliTrak button quickly two times and STABILITRAK COMPETITIVE MODE displays in the Driver Information Center (DIC). While in the Sta ...

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 v ...