2002 CHEVROLET C3500 HD engine

4-40
To engage a PTO while the vehicle is moving:
1. Hold the clutch pedal down.
2. Shift the transmission into NEUTRAL.
3. Engage the PTO.
4. Shift the transmission into the gear you want.
5. Release the clutch as you normally would.
When you release the clutch, the PTO will start.
Variable Mode: PTO speed control mode can be used
for both stationary and mobile applications. This mode
allows PTO to be controlled in a fashion similar to how
cruise control sets vehicle speed. The operator can set an
rpm (between 800 and 2200) with the cruise control
feature or with the SET position on the PTO switch.
The operator is then able to increase rpm in increments
of 100, or ªtap,º with the resume position on the
cruise control. Or, the operator can decrease rpm in
increments of 100 with either of the SET switches on
the PTO or the cruise control. Vehicles not equipped
with cruise control will not be able to increase in
100 rpm increments.Using PTO speed control in Variable Mode:
1. Engage the PTO.
2. Make sure your foot is off the brake pedal
(and off the clutch for vehicles equipped with
a manual transmission).
3. Select the desired engine speed (with the foot pedal)
and select SET on the PTO switch or with the
cruise control.
Engine speed will be governed to the PTO maximum
engine speed (2,200 rpm) while in either the preset or
variable PTO modes. All engine speed values listed
above are factory preset values. With the exception of
the ªtapº increment (100 rpm), all of these values are
programmable and can be adjusted by your GM dealer
or body upfitter. If the PTO software settings do not
match the settings shown here, then they may have
already been altered in order to satisfy the requirements
of the installed PTO system and body equipment.

5-
5-1
Section 5 Problems on the Road
Here you'll find what to do about some problems that can occur on the road.
5
-2 Hazard Warning Flashers
5
-2 Other Warning Devices
5
-3 Jump Starting
5
-9 Towing Your Vehicle
5
-9 Engine Overheating (Gasoline Engine)5
-13 Cooling System (Gasoline Engine)
5
-21 Engine Fan Noise
5
-21 If a Tire Goes Flat
5
-22 Changing a Flat Tire
5
-23 If You're Stuck: In Sand, Mud, Ice or Snow

5-4
If your vehicle has more than one battery, use the
battery that's closer to the starter
-- this will reduce
electrical resistance.
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren't touching
each other. If they are, it could cause a ground
connection you don't want. You wouldn't be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
3. To avoid the possibility of the vehicles rolling, set
the parking brake firmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL before setting the parking brake.
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
4. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off the radio
and all lamps that aren't needed. This will avoid
sparks and help save both batteries. And it could
save your radio!
5. Open the hoods and locate the batteries. Find the
positive (+) and negative (
-) terminal locations
on each vehicle. On vehicles equipped with dual
batteries, make any battery connections to the
primary battery located on the passenger's side of the
vehicle. See ªEngine Compartment Overviewº in the
Index for more information on location.
CAUTION:
If your vehicle has air conditioning, the auxiliary
electric fan under the hood can start up even
when the engine is not running and can injure
you. Keep hands, clothing and tools away from
any underhood electric fan.

5-5
CAUTION:
Using a match near a battery can cause battery
gas to explode. People have been hurt doing this,
and some have been blinded. Use a flashlight if
you need more light.
Be sure the batteries have enough water. You
don't need to add water to the ACDelco
battery
(or batteries) installed in every new GM vehicle.
But if a battery has filler caps, be sure the right
amount of fluid is there. If it is low, add water to
take care of that first. If you don't, explosive gas
could be present.
Battery fluid contains acid that can burn you.
Don't get it on you. If you accidentally get it in
your eyes or on your skin, flush the place with
water and get medical help immediately.
CAUTION:
Fans or other moving engine parts can injure you
badly. Keep your hands away from moving parts
once the engine is running.
6. Check that the jumper cables don't have loose or
missing insulation. If they do, you could get a shock.
The vehicles could be damaged too.
Before you connect the cables, here are some basic
things you should know. Positive (+) will go to
positive (+) or to a remote positive (+) terminal if the
vehicle has one. Negative (
-) will go to a heavy,
unpainted metal engine part or to a negative (
-)
terminal if the vehicle has one. Don't connect
positive (+) to negative (
-) or you'll get a short that
would damage the battery and maybe other parts too.
And don't connect the negative (
-) cable to the
negative (
-) terminal on the dead battery because this
can cause sparks.

5-7
9. Now connect the
black negative (
-)
cable to the
negative (
-)
terminal of the
good battery. Use a
remote negative (
-)
terminal if the
vehicle has one.
Don't let the other end touch anything until the next
step. The other end of the negative (
-) cable doesn't
go to the dead battery. It goes to a heavy, unpainted
metal engine part or to the remote negative (
-)
terminal on the vehicle with the dead battery.
Connect the other end of the negative (-) cable at
least 18 inches (45 cm) away from the dead battery,
but not near engine parts that move. The electrical
connection is just as good there, and the chance of
sparks getting back to the battery is much less.
10. Now start the vehicle with the good battery and run
the engine for awhile.

5-8
11. Try to start the vehicle that had the dead battery.
If it won't start after a few tries, it probably
needs service.
NOTICE:
Damage to your vehicle may result from
electrical shorting if jumper cables are removed
incorrectly. To prevent electrical shorting, take
care that they don't touch each other or any
other metal. The repairs wouldn't be covered by
your warranty.
Jumper Cable Removal
A. Heavy, Unpainted Metal Engine Part or Remote
Negative (
-) Terminal
B. Good Battery or Remote Positive (+) and Remote
Negative (
-) Terminals
C. Dead Battery or Remote Positive (+) Terminal

5-9
To disconnect the jumper cables from both vehicles,
do the following:
1. Disconnect the black negative (
-) cable from the
vehicle that has the dead battery.
2. Disconnect the black negative (
-) cable from the
vehicle with the good battery.
3. Disconnect the red positive (+) cable from the
vehicle with the good battery.
4. Disconnect the red positive (+) cable from the
other vehicle.
Towing Your Vehicle
Consult your dealer or a professional towing service
if you need to have your disabled vehicle towed.
See ªRoadside Assistanceº in the Index.
Engine Overheating
(Gasoline Engine)
You will find a coolant temperature gage on your
vehicle's instrument panel. See ªEngine Coolant
Temperature Gageº in the Index.
If your vehicle has a diesel engine, see ªEngine
Overheatingº in the Diesel Engine Supplement.

5-10 Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
REDUCED ENGINE POWER light is displayed, an
overheat protection mode which alternates firing groups
of cylinders helps prevent engine damage. In this mode,
you will notice a loss in power and engine performance.
This operating mode allows your vehicle to be driven
to a safe place in an emergency. Driving extended
miles (km) and/or towing a trailer in the overheat
protection mode should be avoided.
NOTICE:
After driving in the overheated engine protection
operating mode, to avoid engine damage, allow
the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair
the cause of coolant loss and change the oil. See
ªEngine Oilº in the Index.
If Steam Is Coming From Your Engine