GMC Envoy Owner's Manual page 101

NEUTRAL: Shift the vehicle's transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-51 for
more information.
An indicator light in the knob will show you which
position the transfer case is in. The indicator lights will
come on briefly when you turn on the ignition and
one will stay on. If the lights do not come on, you should
take your vehicle to your dealer for service. An
indicator light will flash while shifting the transfer case. It
will remain illuminated when the shift is complete. If
for some reason the transfer case cannot make a
requested shift, it will return to the last chosen setting.
If the service four-wheel drive light on the instrument
panel cluster stays on, you should take your vehicle to
your dealer for service. See Service Four-Wheel
Drive Warning Light on page 3-48 for further information.
Shifting into 4HI or A4WD
Turn the knob to 4HI or A4WD. This can be done at any
speed unless you are shifting out of 4LO. The indicator
light will flash while shifting. It will remain illuminated
when the shift is complete.
2-28
Shifting into 2HI
Turn the knob to 2HI. This can be done at any speed
unless you are shifting out of 4LO.
Shifting into 4LO
To shift to 4LO, the vehicle's engine must be running and
the vehicle must be stopped or moving less than 2 mph
(3.2 km/h) with the transmission in NEUTRAL (N). The
preferred method for shifting into 4LO is to have your
vehicle moving 1 or 2 mph (1.6 to 3.2 km/h). Turn the
knob to 4LO. You must wait for the 4LO indicator light to
stop flashing and remain illuminated before shifting your
transmission into gear.
If you turn the knob to 4LO when your vehicle is in gear
and/or moving, the 4LO indicator light will flash for
30 seconds and not complete the shift unless your
vehicle is moving less than 2 mph (3.2 km/h) and the
transmission is in NEUTRAL (N). After 30 seconds, the
transfer case will return to the setting last chosen.