2002 CHEVROLET C3500 HD check engine light

2-11 Key in the Ignition
If you leave your vehicle with the keys inside, it's an
easy target for joy riders or professional thieves
-- so
don't do it.
When you park your vehicle and open the driver's door,
you'll hear a tone reminding you to remove your key
from the ignition and take it with you. Always do this.
Your steering wheel will be locked, and so will your
ignition. If you have an automatic transmission, taking
your key out also locks your transmission. Also
remember to lock the doors.
Parking at Night
Park in a lighted spot, close all windows and lock your
vehicle. Remember to keep your valuables out of sight.
Put them in a storage area, or take them with you.
Parking Lots
Even if you park in a lot where someone will be
watching your vehicle, it's still best to lock it up and
take your keys. But what if you have to leave your
ignition key? What if you have to leave something
valuable in your vehicle?

Put your valuables in a storage area, like your
glove box.
If your vehicle has a remote keyless entry system,
take the transmitter with you.

Lock all the doors except the driver's.
Passlock
Your vehicle is equipped with the Passlock
theft
-deterrent system.
Passlock is a passive theft
-deterrent system. Passlock
enables fuel if the ignition lock cylinder is turned with a
valid key. If a correct key is not used or the ignition lock
cylinder is tampered with, fuel is disabled.
During normal operation, the SECURITY light will
go off approximately five seconds after the key is
turned to RUN.
If the engine stalls and the SECURITY light flashes,
wait until the light stops flashing before trying to restart
the engine. Remember to release the key from START
as soon as the engine starts.
If the engine is running and the SECURITY light comes
on, you will be able to restart the engine if you turn the
engine off. However, your Passlock system is not
working properly and must be serviced by your dealer.
Your vehicle is not protected by Passlock at this time.
You may also want to check the fuses. See ªFuses
and Circuit Breakersº in the Index. See your dealer
for service.

2-52
Warning Lights, Gages and
Indicators
Warning lights and gages can signal that something is
wrong before it becomes serious enough to cause an
expensive repair or replacement. Paying attention to
your warning lights and gages could also save you or
others from injury.
Warning lights come on when there may be or is a
problem with one of your vehicle's functions. As you
will see in the details on the next few pages, some
warning lights come on briefly when you start the
engine just to let you know they're working. If you are
familiar with this section, you should not be alarmed
when this happens.
Gages can indicate when there may be or is a problem
with one of your vehicle's functions. Often gages and
warning lights work together to let you know when
there's a problem with your vehicle.When one of the warning lights comes on and stays on
when you are driving, or when one of the gages shows
there may be a problem, check the section that tells you
what to do about it. Please follow this manual's advice.
Waiting to do repairs can be costly
-- and even
dangerous. So please get to know your warning lights
and gages. They're a big help.
Safety Belt Reminder Light
When the key is turned to RUN or START, a tone will
come on for several seconds to remind people to fasten
their safety belts, unless the driver's safety belt is
already buckled.
The safety belt light will
also come on and stay on
for several seconds, then it
will flash for several more.
If the driver's belt is already buckled, neither the tone
nor the light will come on.

2-53 Charging System Indicator Light
This light should come on
briefly when you turn on the
ignition, before starting the
engine, as a check to show
you it is working.
After the engine starts, the light should go out. If it stays
on or comes on while you are driving, you may have a
problem with your charging system. It could indicate a
problem with the generator drive belt, or some other
charging system problem. Have it checked right away.
Driving while this light is on could drain your battery.
If you must drive a short distance with this light on, it
helps to turn off all your accessories, such as the radio
and the air conditioner.
Voltmeter
When your engine is not
running, but the ignition is
in RUN, this gage shows
your battery's state of
charge in DC volts.
When the engine is running, the gage shows the
condition of the charging system. Readings between
the low and high warning zones indicate the normal
operating range.

2-56 Engine Coolant Temperature Gage
This gage shows the engine
coolant temperature.
It also provides an indicator of how hard your vehicle is
working. During a majority of the operation, the gage
will read 210
F (100
C) or less. If you are pulling a
load or going up hills, it is normal for the temperature to
fluctuate and approach the 260
F (125
C) mark. If the
gage reaches the 260
F (125
C) mark, it indicates that
the cooling system is working beyond its capacity.
See ªEngine Overheatingº in the Index.
Malfunction Indicator Lamp (Service
Engine Soon Light in the United States
or Check Engine Light in Canada)
(Gasoline Engine)
United States Canada
Your vehicle is equipped with a computer which
monitors operation of the fuel, ignition and emission
control systems.

2-57
This system is called OBD II (On-Board
Diagnostics
-Second Generation) and is intended to
assure that emissions are at acceptable levels for the
life of the vehicle, helping to produce a cleaner
environment. The SERVICE ENGINE SOON or
CHECK ENGINE light comes on to indicate that there
is a problem and service is required. Malfunctions often
will be indicated by the system before any problem is
apparent. This may prevent more serious damage to
your vehicle. This system is also designed to assist
your service technician in correctly diagnosing any
malfunction.
NOTICE:
If you keep driving your vehicle with this light
on, after a while, your emission controls may not
work as well, your fuel economy may not be as
good and your engine may not run as smoothly.
This could lead to costly repairs that may not be
covered by your warranty.
NOTICE:
Modifications made to the engine, transmission,
exhaust, intake or fuel system of your vehicle or
the replacement of the original tires with other
than those of the same Tire Performance Criteria
(TPC) can affect your vehicle's emission controls
and may cause the SERVICE ENGINE SOON or
CHECK ENGINE light to come on.
Modifications to these systems could lead to
costly repairs not covered by your warranty. This
may also result in a failure to pass a required
Emission Inspection/Maintenance test.
This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If the light doesn't come on, have it repaired.
This light will also come on during a malfunction in one
of two ways:

Light Flashing
-- A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system on your
vehicle. Dealer or qualified service center diagnosis
and service may be required.

2-59
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
ªFuelº in the Index. Poor fuel quality will cause your
engine not to run as efficiently as designed. You may
notice this as stalling after start
-up, stalling when you
put the vehicle into gear, misfiring, hesitation on
acceleration or stumbling on acceleration. (These
conditions may go away once the engine is warmed up.)
This will be detected by the system and cause the light
to turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to fix any mechanical or electrical
problems that may have developed.Emissions Inspection and Maintenance Programs
Some state/provincial and local governments have or
may begin programs to inspect the emission control
equipment on your vehicle. Failure to pass this
inspection could prevent you from getting a vehicle
registration.
Here are some things you need to know in order to help
your vehicle pass an inspection:
Your vehicle will not pass this inspection if the
SERVICE ENGINE SOON or CHECK ENGINE light is
on or not working properly.
Your vehicle will not pass this inspection if the OBD
(on
-board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen if
you have recently replaced your battery or if your
battery has run down. The diagnostic system is designed
to evaluate critical emission control systems during
normal driving. This may take several days of routine
driving. If you have done this and your vehicle still does
not pass the inspection for lack of OBD system
readiness, see your dealer or qualified service center to
prepare the vehicle for inspection.

2-61
CAUTION:
Don't keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches fire. You or others could be burned.
Check your oil as soon as possible and have your
vehicle serviced.
NOTICE:
Damage to your engine from neglected oil
problems can be costly and is not covered by
your warranty.
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused by
a dangerously low oil level or some other problem
causing low oil pressure. Check your oil as soon
as possible.
Security Light
This light will come on
briefly when you turn the
key to START.
The light will come on for five seconds after the key is
turned to ON and then go off. If the light flashes, the
Passlock

System has entered a tamper mode. If the
vehicle fails to start, see ªPasslockº in the Index.
If the light comes on continuously while driving and
stays on, there may be a problem with the Passlock
System. Your vehicle will not be protected by Passlock,
and you should see your GM dealer.

2-62 Up Shift Light (If Equipped)
This light is used on models
with manual transmissions.
The SHIFT indicator light will help you get the best fuel
economy. See ªShift Lightº or ªShift Speedsº in this
section for more information.
Daytime Running Lamps Indicator Light
This light goes on whenever
the DRL are on.
When it begins to get dark, the DRL indicator light
comes on as a reminder to turn on your headlamps.
Check Gages Light
This light will come on
briefly when you are
starting the engine.
If the light comes on and stays on while you are driving,
it could indicate a problem with your vehicle. It could be
a problem with your oil pressure, coolant temperature,
or some other problem. Check your various gages to see
if they are in the warning zones. If they are, have your
vehicle serviced right away.