GMC 2018 Acadia Denali Owner's Manual page 259

258 Driving and Operating
instrument panel contains blunt cut
wires above the parking brake
assembly for the electric trailer
brake controller. The harness
contains the following wires:
Blue: To Trailer
Red/Black or Red/Blue:
Battery Feed
White/Blue: Brake Apply Signal
Black: Ground
The electric trailer brake controller
should be installed by your dealer or
a qualified service center.
Conversions and
Add-Ons
Add-On Electrical
Equipment
Warning
The Data Link Connector (DLC) is
used for vehicle service and
Emission Inspection/Maintenance
testing. See Malfunction Indicator
Lamp (Check Engine Light) 0 128
. A device connected to the DLC
such as an aftermarket fleet or
driver-behavior tracking device
may interfere with vehicle
systems. This could affect vehicle
operation and cause a crash.
Such devices may also access
information stored in the vehicle s
systems.
Caution
Some electrical equipment can
damage the vehicle or cause
components to not work and
would not be covered by the
vehicle warranty. Always check
with your dealer before adding
electrical equipment.
Add-on equipment can drain the
vehicle's 12-volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle 0 83 and Adding Equipment
to the Airbag-Equipped Vehicle
0 84.