See also:

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 communicat ...

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 on page 9‑112. Added electrical equipment ma ...

Lamp Messages
AUTOMATIC LIGHT CONTROL OFF This message displays when the automatic headlamps are turned off. This message clears itself after 10 seconds. AUTOMATIC LIGHT CONTROL ON This message displays when th ...