2007 GMC Sierra 1500 Pickup Owner's Manual - Page 460

Auxiliary Battery The auxiliary battery provision can be used to supply electrical power to additional equipment that you may choose to add, such as a slide-in camper. If your vehicle has this provision, this relay will be located on the passenger's side of the vehicle, next to the auxiliary battery. Notice: Leaving electrical equipment on for extended periods will drain the battery. Always turn off electrical equipment when not in use and do not use equipment that exceeds the maximum amperage rating for the auxiliary battery provision. Power Winches If you wish to use a power winch on your vehicle, only use it when your vehicle is stationary or anchored. Trailer Recommendations You must subtract your hitch loads from the CWR for your vehicle. Weigh your vehicle with the trailer attached, so that you won't go over the GVWR or GAWR. If you are using a weight-distributing hitch, weigh the vehicle without the spring bars in place. You'll get the best performance if you spread out the weight of your load the right way, and if you choose the correct hitch and trailer brakes. For more information, see Towing a Trailer on page 429. When using this provision, connection should only be made to the upper stud (A) of the relay. Do not make connections to the lower stud (B) of the relay. The auxiliary battery circuit is protected by a megafuse located behind the auxiliary battery. Be sure to follow the proper installation instructions that are included with any electrical equipment that you install. 460