CHEVROLET C/K 2003 Owners Manual

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.

2-38
During the first 500 miles (805 km) of vehicle use, start
the vehicle moving in FIRST (1) gear. This allows the
clutch components to wear
-in properly.
FIRST (1): With the vehicle at a stop, release the brake,
press the clutch pedal and shift into FIRST (1). Then,
slowly let up on the clutch pedal as you press the
accelerator pedal. Only downshift into FIRST (1) when
the vehicle has come to a complete stop. If the shift
lever will not go into FIRST (1), put the lever in neutral
and let up on the clutch pedal to fully engage the clutch.
Press the clutch pedal again. Then, shift into FIRST (1).
SECOND (2): With the vehicle at a stop, release the
brake, press the clutch pedal and shift into
SECOND (2). Then, slowly let up on the clutch pedal as
you press the accelerator pedal. With the vehicle
moving, press the clutch pedal and upshift into
SECOND (2) from FIRST (1) while applying light
pressure to the right on the shifter. Then, slowly let up
on the clutch pedal as you press the accelerator pedal.
If you come to a complete stop and the shift lever will
not go into SECOND (2), put the lever in neutral and let
up on the clutch pedal to fully engage the clutch. Press
the clutch pedal again. Then, shift into SECOND (2).THIRD (3): Press the clutch pedal and upshift into
THIRD (3). Then, slowly let up on the clutch pedal as
you press the accelerator pedal.
FOURTH (4), FIFTH (5) and SIXTH (6): Upshift
into the higher forward gears the same way as you do
THIRD (3). Slowly let up on the clutch pedal as you
press the accelerator pedal.
NEUTRAL: Use this position when you start or idle
your engine.
REVERSE (R): To back up, press the clutch pedal.
Wait for the vehicle to stop moving and then, shift to
REVERSE (R). Let up on the clutch slowly while
pressing the accelerator pedal. Also, use REVERSE (R),
along with the parking brake, when turning off your
engine and parking your vehicle.

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.

2-41
To set the hand lever parking brake, pull up on the
handle with your right hand, until it stops.
If the ignition is on when the parking brake is set, the
brake system warning light will come on.
To release the foot pedal parking brake, hold the regular
brake pedal down. Pull the brake release handle, located
just above the parking brake pedal, to release the
parking brake.
To release the hand lever parking brake, push down on
the handle until it stops.
If the ignition is on when the parking brake is released,
the brake system warning light will go off.
NOTICE:
Driving with the parking brake on can cause
your rear brakes to overheat. You may have to
replace them, and you could also damage other
parts of your vehicle. Always check to be sure
your parking brake is fully released before
you drive.
Propshaft Park Brake Burnish Procedure
It is recommended that the propshaft-mounted parking
brake be burnished as part of the new vehicle break
-in.
The parking brake will work best after it has been
burnished following these instructions:
Make 10 stops, using the parking brake hand lever or
foot pedal, from 20 mph (32 km/h) about 2 1/2 miles
(4 km) apart. Between stops, drive the vehicle at
20 mph (32 km/h).

2-42 Air Brake (If Equipped)
CAUTION:
When the yellow SYSTEM PARK and the red
TRAILER AIR SUPPLY knobs are both pushed
in, your rig will be free to move. It could strike
someone or something. When both of these knobs
are pushed in, hold the regular brake pedal down
to keep your rig from moving.
If your vehicle has air
brakes, you will have this
parking brake. It is located
above the radio in the
instrument panel.
Pulling it out applies the parking brake. The park brake
light will come on when the air parking brake is applied.

2-43
Vehicles built for use as tractors or towing vehicles have
two air brake controls. They look like this:To charge a trailer's air brake system do the following:
1. Move your tractor into the proper position.
2. Apply the parking brake by pulling the yellow
parking brake knob out.
3. Hook up the trailer air system properly.
4. Get into the tractor.
5. Push and hold down the regular brake pedal.
6. Push in both the yellow parking brake and the red
trailer air supply knobs. This will charge your
trailer's air system.
After a few minutes, the trailer system should be fully
charged. When it is, the air pressure gage will show
about 125 to 135 psi (862 to 931 kPa).
For driving with a trailer, the yellow and red
(if equipped) knobs must be pushed in. It's the same
when you're not pulling a trailer except that the red
trailer air supply knob must be pulled out.

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.

2-45
Parking Over Things That Burn
CAUTION:
Things that can burn could touch hot exhaust
parts under your vehicle and ignite. Don't park
over papers, leaves, dry grass or other things that
can burn.
Engine Exhaust
CAUTION:
Engine exhaust can kill. It contains the gas
carbon monoxide (CO), which you can't see or
smell. It can cause unconsciousness and death.
You might have exhaust coming in if:

Your exhaust system sounds strange or
different.

Your vehicle gets rusty underneath.

Your vehicle was damaged in a collision.

Your vehicle was damaged when driving over
high points on the road or over road debris.

Repairs weren't done correctly.

Your vehicle or exhaust system had been
modified improperly.
If you ever suspect exhaust is coming into your
vehicle:

Drive it only with all the windows down to
blow out any CO; and

Have your vehicle fixed immediately.