See also:

Customer Assistance Offices (U.S. and Canada)
GMC encourages customers to call the toll-free number for assistance. However, if a customer wishes to write or e-mail GMC, the letter should be addressed to: United States GMC Customer Assistance ...

Horn
Press on the steering wheel pad to sound the horn. ...

Engine Hour Meter Display
The Driver Information Center (DIC) can also display the number of hours the engine has run. To display the engine hours, turn the ignition off, then press and hold the reset button for at least four ...