Using the “Dial” or “Call” Command
1. Press and hold 
for two seconds.
2. Say “Dial” or “Call.” 3. Say the entire number without pausing, or say the name tag.
Once connected, the person called will be heard through the audio speakers.
See also:
Trailer Gain Adjustment Procedure
Trailer Gain should be set for a specific trailering condition and must be adjusted any time vehicle loading, trailer loading, or road surface conditions change.
Setting the Trailer Gain properly is ...
Online Owner Center
Manage your vehicle (U.S.) at gmc.com. Click on “Owners,” then “Manage My GMC/Owners Login.”
Information and services customized for your specific vehicle — all in one convenient place.
...
Engine Coolant
The cooling system in the vehicle is filled with DEX-COOL® engine coolant. The coolant is designed to remain in the vehicle for 5 years or 240 000 km (150,000 mi), whichever occurs first.
The follow ...