GM Chevrolet Avalanche - Manual (Page 333)

Instrument Panel Jumper Wiring Harness
This harness may be included with your vehicle as part
of the heavy-duty trailer wiring package.
This harness is for an electric brake controller and
includes a trailer battery feed fuse. It should be installed
by your dealer or a qualified service center.
Four-Wire Harness Adapter
This adapter may be
included with your vehicle
as part of the heavy-duty
trailer wiring package.
Use this adapter to connect a standard four-way
round pin connector to the seven-wire harness on
your vehicle.
4-73