Chevrolet Avalanche Owner's Manual page 337

Auxiliary Battery
The auxiliary battery provision, if equipped, can be used
to supply electrical power to additional equipment that
you may choose to add.
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.
If your vehicle has this
provision, this relay will be
located on the passenger's
side of the vehicle, next
to the auxiliary battery.
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: 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.
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