2003 Chevrolet Avalanche Owner's Manual - Page 332

Auxiliary Battery The auxiliary battery provision can be used to supply electrical power to additional equipment that you may choose to add. 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. Notice: When using the auxiliary battery provision, the electrical load must not exceed 30 amps. Always turn off any electrical equipment when not in use. Leaving electrical equipment on for extended periods will drain your battery. A I If your vehicle has this provision, this relay will be located on the passenger's side of the vehicle, next to the auxiliary battery. 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. 4-69