GMC T-Series 1999, Owner'S Manual, Page: 57 / 344

yellow blue
2-21
Two
-
Speed Rear Axle Electric Shift
Control (If Equipped)
If your vehicle has this option, you’ll find a label
--
or
labels
--
that show how to use it on the ceiling above the
windshield or in another place near the driver. Be sure to
follow the directions carefully. Use the following
directions based on the type of shift control you have.
Automatic Transmission
The switch is located on the
instrument panel to the right
of the comfort controls.
When the switch is up, the rear axle is in the high range.
Push it down to get the low range.
The two
-
speed axle should be in low range when you
park the vehicle. Apply the parking brake, shift to
PARK (P) or NEUTRAL (N), and shut off the engine.
To operate off
-
road or under a heavy load, shift into low
range when the vehicle is standing still and then operate
the transmission normally.
On the highway, with the axle in low range and
transmission in top gear, you may shift the axle to high
range by raising the switch and releasing the accelerator
momentarily. Reapply the accelerator after your shift.