GMC Yukon 2021 Owner's Manual page 292

Measurement
H2 [(H2 H1)/3]
Tires
Do not tow a trailer while using a
compact spare tire on the vehicle.
Tires must be properly inflated to support
loads while towing a trailer. See Tires
0 339 for instructions on proper tire
inflation.
Safety Chains
Always attach chains between the vehicle
and the trailer, and attach the chains to the
holes on the trailer hitch platform.
Instructions about safety chains may be
provided by the hitch manufacturer or by
the trailer manufacturer.
Cross the safety chains under the tongue of
the trailer to help prevent the tongue from
contacting the road if it becomes separated
H1
H2
H2 H1
(H2 H1)/3
from the hitch. Always leave just enough
slack so the combination can turn. Never
allow safety chains to drag on the ground.
Trailer Brakes
Loaded trailers over 900 kg (2,000 lb) must
be equipped with brake systems and with
brakes for each axle. Trailer braking
equipment conforming to Canadian
Standards Association (CSA) requirement
CAN3-D313, or its equivalent, is
recommended.
State or local regulations may require
trailers to have their own braking system if
the loaded weight of the trailer exceeds
certain minimums that can vary from state
to state. Read and follow the instructions for
the trailer brakes so they are installed,
adjusted, and maintained properly. Never
Driving and Operating
Height Example 1500 (mm)
1 000
1 060
60
20
1 040
attempt to tap into your vehicle's hydraulic
brake system. If you do, both the vehicle
anti-lock brakes and the trailer brakes may
not function, which could result in a crash.
Trailer Wiring Harness
The seven-pin trailer connector is mounted
in the bumper. This connector can be
plugged into a seven-pin universal
heavy-duty trailer connector available
through your dealer.
Use only a round, seven-wire connector with
flat blade terminals meeting SAE J2863
specifications for proper electrical
connectivity.
The seven-wire harness contains the
following trailer circuits:
Yellow/Grey: Left Stop/Turn Signal
291