Horn
Pressa 
on the steering wheel pad
to sound the horn.
See also:
Using the “Delete All Name Tags” Command
This command deletes all stored name tags in the Hands-Free Calling Directory and the OnStar Turn-by-Turn Destinations Directory, if equipped.
To delete all name tags:
1. Press and hold for two sec ...
Responsive driving experience
The '07 Yukon and Yukon Denali are built on GM's new full-size SUV platform,
which incorporates features such as a new, fully boxed frame, coil-over-shock
front suspension and rack-and-pinion stee ...
Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if the vehic ...