OnStar

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Overview
The GMC Sierra All Terrain HD concept is an exploration of heavy-duty truck capability combined with greater off-road versatility. It is highlighted by a bold exterior design, enhanced all-terrain ...

Checking Engine Oil
It is a good idea to check the engine oil level at each fuel fill. In order to get an accurate reading, the vehicle must be on level ground. The engine oil dipstick handle is a yellow loop. See Engine ...

Cruise Control Messages
APPLY BRAKE BEFORE CRUISE If this message displays when attempting to activate cruise control, apply the brake pedal and try again. CRUISE SET TO XXX This message displays when the cruise control ...