See also:

Add-on Electrical Equipment
The OnStar system is integrated into the electrical architecture of the vehicle. Do not add any electrical equipment. See Add-On Electrical Equipment. Added electrical equipment may interfer ...

STEP ON BRAKE TO RELEASE PARK BRAKE
This message is displayed if you attempt to release the electric parking brake without the brake pedal applied. See Parking Brake for more information. ...

Footnotes — Maintenance Schedule Additional Required Services — Severe
a) Check all fuel and vapor lines and hoses for proper hook-up, routing, and condition. Check that the purge valve, if the vehicle has one, works properly. Replace as needed. b) Or every four yea ...