GMC Sierra Owners Manual
Accessory power outlets can be used to plug in electrical equipment, such as a cell phone, MP3 player, etc.
The vehicle may have two accessory power outlets located below the climate control system, or may have one accessory power outlet and one cigarette lighter. The cigarette lighter is designed to fit only in the receptacle closest to the driver.
There may be another accessory power outlet in the rear cargo area.
If the vehicle has a floor console, there is an accessory power outlet inside the storage bin and one on the rear of the floor console.
The accessory power outlets are powered, even when the ignition is in LOCK/OFF. Continuing to use power outlets while the ignition is in LOCK/OFF may cause the vehicle's battery to run down.
See Power Outlets on page 5‑10.