GMC Yukon 2021 Owner's Manual page 375

374 Vehicle Care
8. Release the parking brake only when you
are confident it is secured to tow vehicle
and will not roll.
9. Disconnect the negative battery cable at
the battery and secure the nut and bolt.
Cover the negative battery post with a
non-conductive material to prevent any
contact with the negative battery
terminal.
Caution
Failure to disconnect the negative battery
cable or to have it contact the terminals
can cause damage to the vehicle.
10. Move the steering wheel to make sure
the steering column is unlocked.
Caution
If the steering column is locked, vehicle
damage may occur.
11. Rock the vehicle to make sure the
parking brake is not set and transfer case
is in N (Neutral).
Caution
Towing the vehicle with the parking
brake set can damage it. Always release
the parking brake prior to towing the
vehicle.
Disconnecting the Towed Vehicle
Before disconnecting the towed vehicle:
1. Park on a level surface.
2. Connect the battery.
3. Apply the brake pedal.
Warning
The vehicle can roll when the brake pedal
is released. Always apply and hold the
brake pedal when setting the parking
brake. Make sure the parking brake is
fully engaged before releasing the brake
pedal.
4. Start the engine and shift the transfer
case out of N (Neutral) to 2 . See
Shifting out of N (Neutral) under
Four-Wheel Drive 0 236. See your dealer
if the transfer case cannot be shifted out
of N (Neutral).
5. Check that the vehicle is in 2 by
shifting the transmission to R (Reverse)
and then to D (Drive). There should be
movement of the vehicle while shifting.
6. Shift the transmission to P (Park) and
turn off the vehicle.
7. Set the parking brake.
8. Release the parking brake.
9. Disconnect the vehicle from the tow
vehicle.
10. Reset any lost presets.
The outside temperature display will
default to 0 °C (32 °F) but will reset with
normal usage.