Drive Systems; Four-Wheel Drive - GMC Chevrolet Silverado 2500HD 2021 Owner's Manual

236 Driving and Operating
If equipped with Active Hydraulic Assist, the
vehicle will provide a stiffer steering
response when Tow/Haul mode is engaged
to provide enhanced steering functionality.
Tow/Haul Mode Grade Braking
Tow/Haul Mode Grade Braking is only
enabled while the Tow/Haul Mode is
selected and the vehicle is not in the Range
Selection Mode. See Manual Mode 0 235.
Tow/Haul Mode Grade Braking assists in
maintaining desired vehicle speeds when
driving on downhill grades by using the
engine and transmission to slow the vehicle.
See Towing Equipment 0 276.

Drive Systems

Four-Wheel Drive

If equipped, four-wheel drive engages the
front axle for extra traction.
Read the appropriate section for transfer
case operation before using.
Caution
Do not drive on clean, dry pavement in 4
and 4 (if equipped) for an extended
period of time. These conditions may
cause premature wear on the vehicle s
powertrain.
Driving on clean, dry pavement in 4 or
4 may:
Cause a vibration to be felt in the
steering system.
Cause tires to wear faster.
Warning
If equipped with four-wheel drive, the
vehicle will be free to roll if the transfer
case is in N (Neutral), even when the shift
lever is in P (Park). You or someone else
could be seriously injured. Be sure the
transfer case is in a drive gear
or 4 or set the parking brake before
placing the transfer case in N (Neutral).
See Shifting Into Park 0 230.
Extended high-speed operation in 4
may damage or shorten the life of the
drivetrain.
An engagement noise and bump is normal
when shifting between 4 and 4 or
N (Neutral), with the engine running.
Shifting into 4 will turn Traction Control
and StabiliTrak/Electronic Stability Control
(ESC) off. See Traction Control/Electronic
Stability Control 0 242.
Automatic Transfer Case
Two-Speed Transfer Case
2 , 4 ,
Caution