2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 460

Auxiliary Battery The auxiliary battery provision can be used to supply electrical power to additional equipment that may be added, such as a slide-in camper. If the vehicle has this provision, this relay will be located on the drivers side of the vehicle, next to the underhood electrical center. Be sure to follow the proper installation instructions that are included with any electrical equipment that is installed. 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. Trailer Recommendations Subtract the hitch loads from the Cargo Weight Rating (CWR). CWR is the maximum weight of the load the vehicle can carry. It does not include the weight of the people inside, but you can figure about 150 lbs. (68 kg) for each passenger. The total cargo load must not be more than the vehicles CWR. Weigh the vehicle with the trailer attached, so the GVWR or GAWR are not exceeded. If using a weight-distributing hitch, weigh the vehicle without the spring bars in place. The best performance is obtained by correctly spreading out the weight of the load and choosing the correct hitch and trailer brakes. For more information see Towing a Trailer on page 5‑55. 5-84