
Reducing Speed While Using Cruise
Control
Press in the button at the end of the lever until you
reach the lower speed you want, then release it.
To slow down in very small amounts, tap the button
briefly. Each time you do this, you’ll go 1 mph (1.6 km/h)
slower.
Passing Another Vehicle While Using
Cruise Control
Use the accelerator pedal to increase your speed.
When you take your foot off the pedal, your vehicle will
slow down to the cruise control speed you set earlier.
Using Cruise Control on Hills
How well your cruise control will work on hills depends
upon your speed, load and the steepness of the
hills. When going up steep hills, you may want to step
on the accelerator pedal to maintain your speed.
When going downhill, you may have to brake or shift to
a lower gear to keep your speed down. Of course,
applying the brake or clutch takes you out of cruise
control. Many drivers find this to be too much trouble
and don’t use cruise control on steep hills.
Ending Cruise Control
There are four different ways to turn off the cruise
control:
•Step lightly on the brake pedal (manual and
automatic transmissions).
•Press the clutch pedal to the floor (manual
transmissions).
•Move the cruise switch to off, or
•Shift the transmission to NEUTRAL (N).
Erasing Speed Memory
When you turn off the ignition, your cruise control set
speed memory is erased.
3-12

Interior Lamps
Instrument Panel Brightness Control
This feature controls the brightness of the instrument
panel lights.
The thumbwheel for this feature is located to the right of
the exterior lamp control.
Turn the thumbwheel up to brighten the lights. When
the thumbwheel is moved to the first position, the radio
display and transmission selection display will go to
full intensity. The instrument panel cluster will also be
dimly lit. Moving the thumbwheel up to the next position
will activate the interior dome lamps.
Dome Lamps
The dome lamps will come on when you open a door.
You can also turn the dome lamps on by moving
the thumbwheel, located to the right of the exterior lamp
control, all the way up to the second position. In this
position, the dome lamps will remain on whether a door
is open or closed.
You can use the dome override button to set the dome
lamps to automatically come on when a door is
open, or to remain off.The dome override button is located below the exterior
lamp control.
If the dome override button is pushed in, the dome
lamps will not come on. Use this feature when you want
to leave your door(s) open for an extended period of
time and do not want to run the battery down.
If the dome override button is in the out position, the
interior lamps will work as usual.
3-15

This switchbank is located in the center of the instrument
panel.
e(Marker Lamp Defeat Switch):See “Marker Lamp
Defeat Switch” underExterior Lamps on page 3-13.
j(Manual High Idle Switch):See “Manual High Idle
System” underStarting Your Diesel Engine on
page 2-14.
i(Traction Control Switch):SeeTraction Control
System (TCS) on page 4-11.
f(Outside Heated Mirror Switch):SeeOutside
Heated Mirrors on page 2-41.
g(Power Take Off Switch):SeePower Take-Off
(PTO) on page 4-36.
h(Rear Air Suspension Dump Control
Switch):See “Rear Air Suspension Dump Control”
underTwo-Speed Rear Axle Electric Shift Control
on page 2-26.
k(Rear Axle Shift Control Switch):See “Air Shift
Control” (Automatic Transmission) underTwo-Speed
Rear Axle Electric Shift Control on page 2-26.
Exhaust Brake Switch:SeeDiesel Engine Exhaust
Brake on page 2-25.
l(Differential Lock Control Switch):SeeRear
Axle Differential Lock Control on page 4-10.
cd(Air Bag Off Switch):SeeAir Bag Off Switch
on page 1-55.
If your vehicle does not have some of the features
controlled by these switches, there will be a blank switch
marker in its place.
Accessory Power Outlets
With accessory power outlets, you can plug in auxiliary
electrical equipment such as a cellular telephone or
CB radio.
The accessory power outlets are located on the
passenger’s side of the instrument panel.
To use an outlet, pull the cover down. When not using
it, always cover the outlet with the protective cap.
These circuits are protected by a fuse and have
maximum current levels.
Notice:Leaving electrical equipment on for
extended periods will drain the battery. Always turn
off electrical equipment when not in use and do
not plug in equipment that exceeds the maximum
amperage rating.
3-17

Service Transmission Warning Light
If your vehicle has an Allison automatic transmission,
certain transmission malfunctions will turn this light on.
This light is located with
the auxiliary warning lights
in the center of the
instrument panel.
If this light comes on while you are driving, do not use
the transmission shift control or you may lose forward
gears. The computer for the transmission senses
a problem and chooses a gear to stay in so that you
can drive the vehicle in that gear. You may not be able
to drive as fast or back up when this light is on.
Notice:If you continue driving your vehicle after
the transmission warning light comes on, you could
damage the transmission. While this light is on,
the transmission cannot operate in all gears. If you
attempt to shift gears, the vehicle may not
continue to move. Do not attempt to shift gears
while the transmission warning light is on. Instead,
drive directly to a GM dealer for service. If you
cannot drive to a dealer immediately, have the
vehicle towed.
Range Inhibit Warning Indicator
If your vehicle has an Allison
1000/2000/2200/2400 series automatic transmission, a
lighted bar under the current gear selected will flash.
If your vehicle has an Allison MD automatic
transmission, the current gear selected on the
pushbutton display will flash.
The flashing bar or gear selection indicates that
transmission range shifts may not occur.
For detailed information on shift inhibit limitations, see
the Allison Automatic Transmission Operator’s Manual in
your vehicle for further information.
Brake System Warning Light
Your vehicle has either hydraulic or air brakes. Each
system has different warning lights.
3-31

Transmission Temperature Gage
If you have an automatic
transmission, this gage is
located above the
switchbank in the center of
the instrument panel.
When your ignition is on, the gage shows the
temperature of the transmission oil. A reading in the
warning zone, the red area beginning at 300°F (150°C),
means you must stop driving and check into the
cause. One possible cause is a low oil level in the
transmission.
Notice:If you drive your vehicle with the
transmission temperature gage above normal
operating range, you can damage the transmission.
This could lead to costly repairs that would not
be covered by your warranty. Do not drive your
vehicle while the transmission temperature gage
reading is above normal. See your dealer for service.
Exhaust Brake Indicator Light
If your vehicle is equipped
with an exhaust brake, you
will have this light,
located above the comfort
controls in the center of
the instrument panel.
The exhaust brake indicator light will come on and stay
on whenever the diesel engine exhaust brake or
exhaust restrictor is active. For more information, see
Diesel Engine Exhaust Brake on page 2-25.
Differential Lock Indicator Light
If your vehicle has this
feature, this light is located
in the center of the
instrument panel. The light
is on when the inter-axle
differential lock system
is in use.
The light will come on momentarily during starting. If the
light fails to come on, have it repaired as soon as
possible so you will be aware when the lock system is
in use.
3-40

Traction Control System (TCS)
Your vehicle may have a traction control system that
limits wheel spin. This is especially useful in slippery
road conditions. The system operates only if it senses
that one or both of the rear wheels are spinning or
beginning to lose traction. When this happens,
the system applies the brake(s) at the affected wheel(s).
The bottom light on the TCS on/off button will come
on when the TCS is limiting wheel spin. You may feel or
hear the system working, but this is normal. The TCS
will function at speeds up to about 25 mph (42 km/h).
The TCS may operate on dry roads under some
conditions. When this happens, you may notice a
reduction in acceleration. This is normal and doesn’t
mean there’s a problem with your vehicle. Examples of
these conditions include a hard acceleration in a
turn, an abrupt upshift or downshift of the transmission
or driving on rough roads.
When the light in the top of the TCS button is on, the
TCS is off and will not limit wheel spin. Adjust your
driving accordingly.
The light in the top of the TCS button will come on if the
TCS is turned off by pressing the TCS on/off button.
The light may also come on if a problem has been
detected in either the traction control system or
the anti-lock brake system.The traction control system automatically comes on
whenever you start your vehicle. To limit wheel
spin, especially in slippery road conditions, you should
always leave the system on. But you can turn the
traction control system off if you ever need to. You
should turn the system off if your vehicle ever gets stuck
in sand, mud or snow and rocking the vehicle is
required. SeeRocking Your Vehicle To Get it Outunder
If You Are Stuck: In Sand, Mud, Ice or Snow on
page 4-29.
To turn the system on or
off, press the traction
control button located in
the instrument panel
switchbank.
If you used the TCS button to turn the system off, the
light in the top of the button will come on and stay
on. You can turn the TCS back on at any time by
pressing the button again; the light should go off.
4-11

Here are some tips that can make your drive through
steep country safer:
•Keep the vehicle in good shape. Check all fluid
levels and also the brakes, tires, cooling system
and transmission. These parts can work hard
on mountain roads.
•Know how to go down hills. The most important
thing to know is this: let your engine do some of
the slowing down. Shift to a lower gear when you go
down a steep or long hill.
{CAUTION:
If you do not shift down, your brakes could get
so hot that they would not work well. You
would then have poor braking or even none
going down a hill. You could crash. Shift down
to let your engine assist your brakes on a
steep downhill slope.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have
to do all the work of slowing down. They could
get so hot that they would not work well. You
would then have poor braking or even none
going down a hill. You could crash. Always
have your engine running and your vehicle in
gear when you go downhill.
•Know how to go uphill. Use lower gears. They help
cool your engine and transmission, and you can
climb the hill better.
•Stay in your own lane when driving on two-lane
roads in hills or mountains. Do not swing wide
or cut across the center of the road. Drive at speeds
that let you stay in your own lane.
•As you go over the top of a hill, be alert. There
could be something in your lane, like a stalled car or
an accident.
•You may se highway signs on mountains that warn
of special problems. Examples are long grades,
passing or no-passing zones, a falling rocks area,
winding roads and special truck lanes. Be alert
to these and take appropriate action.
4-24

If you have a diesel engine, you may have to run it at a
higher speed to get enough heat.
Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine
again and repeat this only when you feel really
uncomfortable from the cold. But do it as little as
possible. Preserve the fuel as long as you can. To help
keep warm, you can get out of the vehicle and do
some fairly vigorous exercises every half hour or so until
help comes.
If You Are Stuck: In Sand, Mud, Ice
or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you do not want to
spin your wheels too fast. The method known as
“rocking” can help you get out when you are stuck, but
you must use caution.
{CAUTION:
If you let your tires spin at high speed, they
can explode, and you or others could be
injured. And, the transmission or other parts of
the vehicle can overheat. That could cause an
engine compartment re or other damage.
When you are stuck, spin the wheels as little
as possible. Do not spin the wheels above
35 mph (55 km/h) as shown on the
speedometer.
Notice:Spinning your wheels can destroy parts of
your vehicle as well as the tires. If you spin the
wheels too fast while shifting your transmission
back and forth, you can destroy your transmission.
4-29