Customer Assistance for Text Telephone (TTY) Users (U.S. and Canada)
To assist customers who are deaf, hard of hearing, or speech impaired and who use Text Telephones (TTYs), GMC has TTY equipment available at its Customer Assistance Center. Any TTY user can communicate with GMC by dialing:
1-800-462-8583. TTY users in Canada can dial 1-800-263-3830.
See also:
Manual Seats
Manual Seats
A. Seat Adjustment Handle
B. Driver Seat Height Adjustment Lever
C. Seatback Lever
To adjust a manual seat:
1. Lift the handle (A) under the seat to unlock it.
2. Slide the seat ...
Heated Mirrors
For vehicles with heated mirrors:
The heated outside rearview mirrors turn on when the rear window defogger is
on and help to clear fog or frost from the surface of the mirrors.
(Rear Window Defo ...
Overheated Engine Protection Operating Mode
If an overheated engine condition exists and the ENGINE POWER IS REDUCED message displays, an overheat protection mode which alternates firing groups of cylinders helps to prevent engine damage. In th ...





