GMC 2003 Sierra 1500 Pickup Owner's Manual page 296

The 4 Wheel Steer system is equipped with three
different driving modes:
Two wheel steering (2)
Four wheel steering (4)
*
Four wheel steering with a trailer mode
(q
)
4 : -
0
0 9
0 0
U
I I
2
4
=wF
2: In this mode the vehicle will operate like any other
vehicle with two wheel steering. If you want to use
2 wheel steer mode and your vehicle is not in this mode,
press the button until the 2 indicator, located to the
right of the 4 Wheel Steer button, lights up. If the
2 indicator is flashing you will have to center the steering
wheel by turning it to the left or right.
Your vehicle will return to 2 when the transmission is
shifted into NEUTRAL, for example when entering a
car wash.
If you want to use tire chains, the vehicle needs to be
in 2 wheel steer mode.
4: In this mode all four wheels will help steer the vehicle.
If you want to use 4, and your vehicle is not in this mode,
press the button, until the 4 indicator, located to the right
of the 4 Wheel Steer button, comes on and stays on. If
the 4 indicator is flashing you will have to center the
steering wheel by turning it to the left or right.
The switch is located on the instrument panel.
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