See also:

Manual Operation of Power Liftgate
To change the liftgate to manual operation, turn the mode switch to the OFF position. With the power liftgate disabled and all of the doors unlocked, the liftgate can be manually opened and closed. ...

OnStar Mobile App
With an iPhone® or Android™-based mobile device, an OnStar mobile app can be downloaded. The vehicle can be remote started, if equipped, or the doors can be unlocked from anywhere there is cell ...

Horn
To sound the horn, press the center pad on the steering wheel. ...