GMC 2005 Canyon Owner's Manual page 109

Indicator lights in the buttons show you which setting
you are 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 in
for service. An indicator light will flash while shifting.
It will remain illuminated when the shift is completed.
If for some reason the transfer case cannot make
a requested shift, it will return to the last chosen setting.
Shifting from Two-Wheel High to
Four-Wheel High
Press and release the four-wheel high button. This can
be done at any speed, and the front axle will lock
automatically.
Shifting from Four-Wheel High to
Two-Wheel High
Press and release the two-wheel high button. This can
be done at any speed, and the front axle will unlock
automatically.
Shifting from Two-Wheel High or
Four-Wheel High to Four-Wheel Low
To shift from two-wheel high or four-wheel high to
four-wheel low, the vehicle must be stopped or moving
less than 1.2 mph (2 km/h) with the transmission in
NEUTRAL (N) in vehicles equipped with an automatic
transmission or the clutch pedal engaged in vehicles
equipped with a manual transmission. The preferred
method for shifting into four-wheel low is to have your
vehicle moving 1.2 mph (2 km/h). Press and release the
four-wheel low button. You must wait for the four-wheel
low indicator light to stop flashing and remain
illuminated before shifting your transmission into gear or
releasing the clutch pedal.
If the four-wheel low button is pressed when your
vehicle is in gear and/or moving faster than 1.2 mph
(2 km/h), the four-wheel low indicator light will flash for
30 seconds and not complete the shift.
On automatic transmission equipped vehicles, if your
transfer case does not shift into four-wheel low,
your transmission indicator switch may require
adjustment. With your transmission in NEUTRAL (N),
press and release the four-wheel low button.
While the four-wheel low indicator light is flashing,
shift your transmission into PARK (P). Press the
four-wheel low button again. Wait until the four-wheel
low indicator light remains illuminated before shifting
your transmission into gear. Press the four-wheel
low button again to complete the shift. This will get you
into four-wheel low, but you should take your vehicle
in for service to restore normal operation.
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