GMC Sierra 2500 HD2022 Owner's Manual page 380

Warning
To avoid death, serious injury,
or property damage, before dinghy
towing the vehicle, always disconnect and
secure the negative battery cable and
cover the negative battery post and cable
with a non-conductive material. If the
battery is left connected or the battery
cable contacts the post, the Electric
Parking Brake may activate during
towing, which could cause a crash.
8. Disconnect the negative ( ) battery
cable. See Negative Battery Cable
Disconnection in Battery - North
America 0 324.
9. Shift the transmission to P (Park).
Caution
If the steering column is locked, vehicle
damage may occur.
10. Move the steering wheel to make sure
the steering column is unlocked.
11. If the vehicle has an ignition key, keep it
in the towed vehicle in ACC/ACCESSORY
to prevent the steering column from
locking. If the vehicle is equipped with
Keyless Access, keep the RKE transmitter
outside of the vehicle and manually lock
the doors. Access the vehicle by using
the key in the door lock. See Door Locks
0 21.
Disconnecting the Towed Vehicle
Before disconnecting from the tow vehicle:
1. Park on a level surface. Secure the
vehicle with wheel blocks.
2. Re-connect the negative ( ) battery. See
Battery - North America 0 324.
3. Turn on the ignition with the engine off.
For vehicles with a key, turn the ignition
to ON/RUN with the engine off. If the
vehicle is equipped with Keyless Access,
with your foot off the brake pedal, press
and hold ENGINE START/STOP for
five seconds until the green light comes
on in the button. See Ignition Positions
(Keyless Access) 0 229 or
Ignition Positions (Key Access) 0 227.
4. Set the parking brake. See Electric
Parking Brake 0 245.
5. Disconnect from the tow vehicle.
6. Shift the transmission to N (Neutral).
Vehicle Care
7. Shift the transfer case to 2 (Two-Wheel
Drive High). When the shift to 2
(Two-Wheel Drive High) is complete, the
light in the instrument cluster will stop
flashing and stay lit. See
Four-Wheel-Drive Light 0 119.
8. Start the engine. Check that the vehicle
is in 2 (Two-Wheel Drive High) by
starting the engine and shifting the
transmission to D (Drive) and then to
R (Reverse). There should be movement
of the vehicle while shifting.
9. Shift the transmission to P (Park) and
turn off the ignition.
10. Release the parking brake and remove
the wheel blocks.
11. Reset any lost presets.
The outside temperature display will
default to 0 °C (32 °F) but will reset with
normal usage.
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