2001 GMC SIERRA check engine light

2-17
Testing the Alarm
The alarm can be tested by following these steps:
1. From inside the vehicle, lower the driver's window
and open the driver's door.
2. Activate the system by locking the doors with the
power door lock switch while the door is open, or
with the remote keyless entry transmitter.
3. Get out of the vehicle, close the door and wait for the
SECURITY message to go out.
4. Then reach in through the window, unlock the door
with the manual door lock and open the door.
This should set off the alarm.
If the alarm does not sound when it should but the
vehicle's headlamps flash, check to see if the horn
works. The horn fuse may be blown. To replace the fuse,
see ªFuses and Circuit Breakersº in the Index.
If the alarm does not sound or the vehicle's headlamps
do not flash, the vehicle should be serviced by an
authorized service center.
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.
If the engine stalls and the SECURITY message 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 message
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 fuse (see ªFuses and
Circuit Breakersº in the Index). See your dealer
for service.
In an emergency, call the GM Roadside Assistance
Center. See ªRoadside Assistanceº in the Index.

2-78
Safety and Security Services

Automatic Notification of Air Bag
Deployment
-- If an air bag deploys, a priority
emergency signal is sent automatically to the center.
An advisor will locate your vehicle's position, try to
contact you and assist you in the situation. If the
center is unable to contact you, an emergency service
provider will be contacted.

Stolen Vehicle Tracking
-- Call the center at
1
-888-4-ONSTAR (1-888-466-7827) to report your
vehicle stolen. The system can then locate and track
your vehicle and the advisor will be able to notify
the proper authorities.

Roadside Assistance with Location
-- For vehicle
breakdowns, press the OnStar button. An advisor
will contact the appropriate help.

Remote Diagnostics
-- If an instrument panel
light comes on, the center can perform a check of
the engine on
-board computer. An advisor can then
recommend what action needs to be taken.
OnStar MED
-NET -- Med-Net can store your
personal medical history and provide it to emergency
personnel if necessary.

Accident Assist
-- An advisor can provide
step
-by-step guidance following an accident.

Remote Door Unlock
-- To contact the center, call
1
-888-4-ONSTAR. You will be required to provide
your security information. An advisor will send a
command to your vehicle to unlock itself. The
advisor can delay unlocking your vehicle. Remote
Door Unlock is disabled 48 hours after the vehicle is
parked to maintain the battery charge.

Vehicle Locator Service
-- To contact the center,
call 1
-888-4-ONSTAR. You will be required to
provide your security information. An advisor will
send a command to your vehicle to sound the horn
and/or flash the lamps.
In order to provide you with excellent service, calls with
the OnStar Center may be monitored or recorded.

2-84
Warning Lights, Gages
and Indicators
This part describes the warning lights and gages that
may be on your vehicle. The pictures will help you
locate them.
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.
Your vehicle may also have a driver information system
that works along with the warning lights and gages.
See ªMessage Centerº in the Index.
Safety Belt Reminder Light
When the key is turned to RUN or START, a chime will
come on for about six 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 about 20 seconds, then
it will flash for
about 55 seconds.
If the driver's belt is already buckled, neither the chime
nor the light will come on.

2-93
The TRACTION OFF light may come on for the
following reasons:

If you turn the system off by pressing the TAS on/off
button the light will come on and stay on. To turn the
system back on, press the button again; the light
should go off.

If you move the shift lever to FIRST (1), the light
will come on and stay on to indicate that the Traction
Assist System is off. This is normal operation. To
turn the system back on, move the shift lever back to
a position other than FIRST (1); the light should go
off. See ªTraction Assist Systemº in the Index.

The light will come on and stay on if the TAS automatic
engagement feature has been turned off. To turn the
system on, press the TAS off/on button; the light should
go off. To turn the automatic engagement feature back
on, see ªTraction Assist Systemº in the Index.

If the Traction Assist System is affected by an
anti
-lock brake system, Traction Assist System or
engine
-related problem, the system will turn off and
the light will come on. Have your vehicle serviced.

If the vehicle is driven over an extremely rough road,
the system will turn off and the light will come on.
The light will go off a few seconds after the rough
road conditions go away or when the vehicle comes
to a complete stop. This is normal operation.
Malfunction Indicator Lamp (Service
Engine Soon Light in the United States or
Check Engine Light in Canada)
United States Canada
Your vehicle is equipped with a computer which monitors
operation of the fuel, ignition and emission control systems.
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.

2-94
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 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.

Light On Steady
-- An emission control system
malfunction has been detected on your vehicle.
Dealer or qualified service center diagnosis and
service may be required.
If the Light Is Flashing
The following may prevent more serious damage to
your vehicle:

Reducing vehicle speed.

Avoiding hard accelerations.

Avoiding steep uphill grades.

If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.

2-95
If the light stops flashing and remains on steady, see
ªIf the Light Is On Steadyº following.
If the light continues to flash, when it is safe to do so,
stop the vehicle. Find a safe place to park your vehicle.
Turn the key off, wait at least 10 seconds and restart the
engine. If the light remains on steady, see ªIf the Light
Is On Steadyº following. If the light is still flashing,
follow the previous steps, and drive the vehicle to your
dealer or qualified service center for service.
If the Light Is On Steady
You may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. See ªFilling Your Tankº in the Index. The
diagnostic system can determine if the fuel cap has been
left off or improperly installed. A loose or missing fuel
cap will allow fuel to evaporate into the atmosphere. A
few driving trips with the cap properly installed should
turn the light off.Did you just drive through a deep puddle of water?
If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out. A few driving trips should turn the light off.
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.

2-96
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.
Oil Pressure Gage
United States Canada
The oil pressure gage shows the engine oil pressure in
psi (pounds per square inch) when the engine is running.
Canadian vehicles indicate pressure in kPa (kilopascals).
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. See ªCheck Eng Oil Pressureº and
ªEngine Oilº in the Index.

2-97
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.
Cruise Light (If Equipped)
United States Canada
The CRUISE light comes on whenever you set your
cruise control. See ªCruise Controlº in the Index.
4WD Light (If Equipped)
The 4WD indicator will
light up when you shift a
manual transfer case into
four
-wheel drive and the
front axle engages.
Some delay between shifting and the indicator's lighting
is normal.
See ªFour
-Wheel Driveº in the Index for more information.