GMC 2009 Sierra - Manual (Page 312)

• Red: Battery Feed*
• Dark Blue: Trailer Brake*
*The fuses for these two circuits are installed in the
underhood electrical center, but the wires are not
connected. They should be connected by your
dealer/retailer or a qualified service center. The fuse for
the battery feed is not required if your vehicle has an
auxiliary battery. If your vehicle does not have an
auxiliary battery, have your dealer/retailer or authorized
service center install the required fuse.
If you are charging a remote (non-vehicle) battery, press
the tow/haul mode button located at the end of the
shift lever. This will boost the vehicle system voltage and
properly charge the battery. If the trailer is too light for
tow/haul mode, you can turn on the headlamps as
a second way to boost the vehicle system and charge
the battery.
Electric Brake Control Wiring
Provisions
These wiring provisions are included with your vehicle
as part of the trailer wiring package. These provisions
are for an electric brake controller. The instrument panel
contains blunt cut wires near the data link connector
for the trailer brake controller.
The harness contains the following wires:
• Dark Blue: Brake Signal to Trailer Connector
• Red/Black: Battery
• Light Blue/White: Brake Switch
• White: Ground
It should be installed by your dealer/retailer or a
qualified service center.
Trailer Recommendations
You must subtract your hitch loads from the CWR for
your vehicle. Weigh your vehicle with the trailer
attached, so that you won’t go over the GVWR or
GAWR. If you are using a weight-distributing hitch,
weigh the vehicle without the spring bars in place.
You’ll get the best performance if you spread out the
weight of your load the right way, and if you choose the
correct hitch and trailer brakes.
For more information, see Towing a Trailer on
page 4-41.
4-54