GMC 2002 Yukon Denali Owner's Manual page 258

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The seven wire harness contains the following
trailer circuits:
D
Yellow: Left Stop/Turn Signal
D
Dark Green: Right Stop/Turn Signal
D
Brown: Taillamps
D
White: Ground
D
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Light Green: Back up Lamps
D
Red: Battery Feed
D
Dark Blue: Trailer Brake
A jumper harness for an electric trailer brake controller
and a trailer battery feed fuse are included with this
trailering package. (See "Instrument Panel Jumper
Wiring Harness" later in this section.)
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If you need to tow a light
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four way round pin connector, an adapter connector is
included with the vehicle. See "Four
Harness Adapter" later in this section.
duty trailer with a standard
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Wire Trailer
Instrument Panel Jumper Wiring Harness
This harness is included with the heavy
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camper/fifth wheel trailer wiring packages. The harness
is for an electric trailer brake controller and includes a
trailer battery feed fuse. This harness and fuse should be
installed by your dealer or a qualified service center.
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duty and
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