transmission CHEVROLET C/K 2003 User Guide

2-30
Diesel Engine Exhaust Brake
(If Equipped)
The exhaust brake is available on vehicles equipped
with a diesel engine. It is located in the exhaust system.
The exhaust brake is used to help slow the vehicle and
may assist the vehicle's foundation brakes. The use of
the exhaust brake will assist the braking of the vehicle
and prolong the life of the foundation brake lining
material.
The exhaust brake switch is
located in the instrument
panel switchbank.Push the bottom of the switch to turn the exhaust brake
on. When you push the top of the switch, the exhaust
brake will turn off.
There is an indicator light on the instrument panel
similar to the symbol on the switch, that will come on
when the exhaust brake is active. See ªExhaust Brake
Indicator Lightº in the Index for more information.
When using the exhaust brake, the proper gear range
selection is important. The exhaust brake will be most
effective if the gear range selected is the lowest possible
range that does not allow the engine rpm to go more
than 200 rpm above rated (full load) rpm. If you have a
Caterpillar diesel engine, do not exceed 2900 rpm. If
you have a DURAMAX (LG4) diesel engine, do not
exceed 3200 rpm. If you have a DURAMAX (LB7)
diesel engine, do not exceed 3600 rpm.
If you have an automatic transmission and press this
button, the transmission will downshift to a factory
default setting of fourth gear. To change the default
setting, or for more information on factory default
settings, contact your dealer for assistance.

2-31
The accelerator and clutch pedals must be released in
order for the exhaust brake to engage. The exhaust brake
will not function when the cruise control feature is
active, and will automatically shut off when the
anti
-lock brake system is active.
CAUTION:
Be careful when using the exhaust brake or you
could lock the wheels and lose control of the
vehicle. Operators not familiar with an exhaust
brake should not use this brake on slippery
surfaces before learning to use it on dry surfaces.
If the vehicle's wheels begin to lock when using
the exhaust brake on slippery surfaces, switch the
exhaust brake off immediately. The exhaust
brake will turn off if the anti
-lock brake system
is activated.
Tw o-Speed Rear Axle Electric Shift
Control (If Equipped)
If your vehicle is equipped with this feature, you'll find
a label on the headliner above the windshield or in
another place near the driver that shows how to use it.
Be sure to follow the directions carefully.
Use the following directions based on the type of shift
control you have.
Manual Transmission
The rear axle shift control
switch for a manual
transmission is located
on the shift lever.
When the switch is up, the rear axle is in the high range.
Push the switch down to change to low range.

2-32
The two-speed axle should be in low when you park the
vehicle. You'll need to engage the transmission, even
move the vehicle a little, to be sure the axle is in the low
range. Then apply the parking brake, shift into
NEUTRAL and shut off the engine.
Also, always start the vehicle in motion with the
two
-speed axle in the low range. To shift up from low to
high, do the following:
1. Move the switch up for the high range,
2. disengage the clutch, and
3. after a brief pause, engage the clutch and then press
down on the accelerator.
To shift down from high to low, do the following:
1. Move the switch down to low,
2. release the accelerator and then quickly apply
it again.
Automatic Transmission
The rear axle shift control
switch for an automatic
transmission is located in
the instrument panel
switchbank.
Press the bottom of the switch to get to the low range.
The switch indicator light will come on when the
vehicle is in low range. Press the top of the switch to
return to the high 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.

2-33
On the highway, with the axle in low range and the
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 you shift.
Under light load conditions, first shift the axle into the
high range with the vehicle at a standstill and then
operate the transmission normally.
Air Shift Control (Automatic Transmission)
The switch for the rear axle
shift control is located in the
instrument panel
switchbank.
Press the bottom of the switch to get to the low range.
Press the top of the switch to return to the high range.The two
-speed axle should be in low when you park
the vehicle.
You'll need to engage the transmission, even moving the
vehicle a little, to be sure the axle is in low range. Then
shift into PARK (P), apply the parking brake and shut
off the engine.
Also, always start the vehicle in motion with the
two
-speed axle in the low position. To shift up from
low to high, press the top of the rear axle shift control
switch and press down on the accelerator. When you
shift the axle from high to low, press the bottom of the
switch, release the accelerator and then quickly press it
down again.
Air Suspension (If Equipped)
Your vehicle may be equipped with the Hendrickson
HAS Series single
-axle air suspension which is designed
for single
-axle on-highway use. The feature is available
in 19,000 lb. (8 618.3 kg), 21,000 lb. (9 525.4 kg) and
23,000 lb. (10 432.6 kg) capacities for operations which
require extra cubic capacity and a reduced deck height.

2-34 Rear Air Suspension Dump Control
If your vehicle is equipped with the Hendrickson HAS
Series single
-axle air suspension, you have this control.
The air suspension dump control allows the operator to
lower the deck height approximately 4.5 inches
(11.5 cm) from the normal frame height.
The switch to deflate and
inflate the air suspension is
located in the instrument
panel switchbank.
Press the bottom of the switch to deflate the air
suspension and lower the deck height. Press the top
of the switch to return the suspension to normal
deck height.
An indicator light will come on and stay on whenever
the switch is in the dumped position.
Automatic Transmission Operation
We build vehicles with five and six-speed automatic
transmissions. This part of the manual covers the basics
of these. With some of the transmissions, you will find
another manual in your vehicle that goes into more
detail. On the headliner, in front of and above the driver,
or in some other place near the driver, you will see a
label that describes important operating facts about the
automatic transmission in your vehicle. Make sure you
follow the instructions on this label.
Be sure to keep your parking brake set until you are
ready to shift into DRIVE (D), and press the brake pedal
while shifting from NEUTRAL (N) or PARK (P) to a
drive gear.
All vehicles equipped with automatic transmissions
can be started in PARK (P), if equipped, or in
NEUTRAL (N). See the Allison

Transmission
Operator's Manual in your vehicle for more information
about this.

2-36 Overdrive Defeat (If Equipped)
If your vehicle has this feature, you can select not to
shift up to fifth gear. This is useful when towing or
under a heavy load.
The overdrive defeat switch
is located in the instrument
panel to the right of the
steering column.
Press the switch to limit the transmission to fourth gear.
This will allow for better fuel economy and fewer
downshifts while pulling a tractor or trailer or under a
heavy load. The indicator light in the switch will come
on whenever overdrive defeat is active.
Manual Transmission Operation
Using the Clutch
When you're starting to move the vehicle, it's important
to begin with the engine speed at idle. Then start to
engage the clutch and listen for an engine speed drop
of about 100 rpm. At this point, the clutch is engaging,
so you should increase the engine speed and fully
engage the clutch. It's important not to increase the
engine speed sooner or before the clutch begins it's
engagement. If you do, you can cause damage to
your vehicle.
Double-Clutching
You must use the double-clutching method when you
shift an unsynchronized gear set. Disengage the clutch,
shift to neutral and engage the clutch. When upshifting,
slow the engine until the engine rpm and road speed
match. When downshifting, accelerate the engine until
the engine rpm and road speed match. Then quickly
disengage the clutch and move the shift lever to the next
gear position and engage the clutch.

2-37 Eaton Fuller Five and Six-Speed
Transmissions and TTC Spicer
Seven-Speed Transmissions
These transmissions have gears that automatically
synchronize when you shift up or down (except
FIRST (1) gear on the five
-speed and seven-speed
transmission which is unsynchronized). Choose the gear
that will maintain the road speed you want while
keeping the engine above two
-thirds of the governed
speed. When the engine speed drops below two
-thirds of
the governed speed, shift into the next lower gear before
your engine begins to lug. When you shift down, be sure
to double
-clutch if required.
ZF Six-Speed Transmission
Here's how to operate
your transmission.
This six
-speed pattern is unique to GM manual
transmissions. The transmission always repositions
the shift lever to neutral, which is located between
FOURTH (4) and FIFTH (5) gear.
To prevent unintentional gear selections, additional
force is required to move the shift lever into
REVERSE (R) or FIRST (1). Use FIRST (1) when
trailer towing, driving with payload in the pickup box or
launching on a grade. Otherwise, start in SECOND (2)
gear. Only shift into FIRST (1) when the vehicle has
stopped moving.

2-39 Eaton Fuller Nine and Ten-Speed
Non-Synchronized Manual Transmissions
(If Equipped)
If your vehicle has one of these unsynchronized
transmissions, it's naturally somewhat complicated.
The label above the windshield will tell you the
operating basics you need to know.
The following are driving tips.

Always choose an initial starting gear suitable for
the load and terrain.

Always use double
-clutching procedures
when shifting.

Never move the range shift lever to the LO speed
gear position after HI range preselection, or anytime
the transmission is in the HI range.

Never move the range knob or lever with the shift
lever in NEUTRAL while the vehicle is moving.

Never make a range shift while moving
in REVERSE (R).
Clutch Brake (Vehicles with
Non-Synchronized Transmission)
A clutch brake is used to stop transmission input shaft
rotation so that FIRST (1) or REVERSE (R) gear
selection can be initiated when the vehicle is at a
standstill and the engine is idling.
Press the clutch pedal all the way down to the
floorboard to apply the clutch brake.
When using the clutch brake, disengage the clutch pedal
and shift the transmission into either the initial starting
gear or REVERSE (R). If the tooth
-butting occurs
between the clutching teeth, re
-engage the clutch while
applying light pressure to the shift lever. This will
provide for a smooth shift into either FIRST (1) or
REVERSE (R) gear.
NOTICE:
After engaging FIRST (1) or REVERSE (R) gear,
do not use the clutch brake for upshifting and
downshifting. To do so will shorten the service life
of the clutch brake and gear selection shift efforts
may be increased.

2-40
Parking
CAUTION:
If you don't park your vehicle properly, it can
roll. If you've left the engine running, it can move
very quickly. You or others could be injured. To
be sure your vehicle won't move, even when
you're on level ground, follow the steps below.
Two-Speed Rear Axle
1. With the engine running, shift the two-speed rear
axle into low. To be sure it's in low, you'll need to
move the vehicle in gear just a little.
2. Hold the regular brake pedal down with your
right foot.
3. Apply the parking brake.
4. Shift the transmission to NEUTRAL or PARK (P).
Hydraulic Brakes (If Equipped)
If your vehicle has hydraulic brakes, it has either a
parking brake foot pedal or hand lever. If you have the
parking brake foot pedal, it is located below the
instrument panel to the left of the steering column.
If you have the parking brake hand lever, it is located to
the right of the driver, on the floor.
To set the foot pedal parking brake, hold the regular
brake pedal down with your right foot. Push down the
parking brake pedal with your left foot.

2-44
CAUTION:
If you apply any one of the air brake parking
controls while the vehicle is moving, your rig will
stop suddenly. If you are not ready for this, you
or others could be injured. Don't apply any one
of these controls while you're driving, unless you
have to make an emergency stop.
If the air pressure drops below 60 to 70 psi (413 to
482 kPa), the primary brake light and warning buzzer
will come on. If the air pressure drops to 35 to 45 psi
(241 to 310 kPa), the red trailer air supply knob will
automatically pop out and apply the spring brakes on
the trailer.If the air pressure drops to 35 to 45 psi (241 to 310 kPa),
the yellow park brake knob will automatically pop out
and apply the spring brakes on the truck or tractor.
If you ever have a complete loss of air so that your air
brakes automatically apply, there is a way that the tow
operator can release the parking brakes to tow the
vehicle. See ªTowing Your Vehicleº in the Index.
CAUTION:
If your vehicle is left in gear, the engine can start
if the vehicle starts to roll. This can easily happen
if you have the diesel engine. Shift the
transmission into NEUTRAL (N) before you
leave the vehicle.