2002 GMC SIERRA engine

2-46
Electrochromic Mirror Operation
The electrochromic (self
-dimming) mirror function is
turned on automatically each time the engine is started.
To operate the electrochromic mirror do the following:
1. Make sure the green indicator light, located to the
left of the on/off button, is lit. If it's not, press and
hold the on/off button for six seconds until the
green light comes on, indicating that the mirror
is in electrochromic (self dimming) mode.
2. Turn off the electrochromic mirror function by
pressing and holding the on/off button for six
seconds until the green indicator light turns off.
Compass Variance
The mirror is set in zone eight upon leaving the factory.
It will be necessary to adjust the compass to compensate
for compass variance if you live outside of zone eight.
Under certain circumstances, as during a long distance
cross
-country trip, it will be necessary to adjust for
compass variance. Compass variance is the difference
between earth's magnetic north and true geographic
north. If not adjusted to account for compass variance,
your compass could give false readings.To adjust for compass variance do the following:
1. Find your current location and variance zone number
on the following zone map.
2. Press and hold the on/off button for nine seconds or
until a Z and a zone number appears in the display.
The compass is now in zone mode.

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The light will be red in the event of an OnStar system
malfunction. If this occurs press the OnStar button to
attempt to contact an advisor. If the connection is made,
the advisor will assist you with steps to take to make
sure that the system is functioning properly. If you
cannot contact the advisor, take your vehicle to your
dealership as soon as possible for assistance.
Cellular Antenna: The cellular antenna on the outside
of your vehicle is critical to effective communication
using the OnStar system. Optimum cellular reception
can be obtained when the mast is straight up and down.
OnStar Services
The following services are available within OnStar service
plans. Your vehicle comes with a specific one
-year service
plan that allows use of some or all of the following 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 attempt to locate
and track your vehicle and the advisor will assist the
proper authorities.
Roadside Assistance with Location: For vehicle
breakdowns, press the OnStar Services button.
An advisor will contact the appropriate help.
Remote Diagnostics: If an instrument panel light comes
on, press the OnStar Services button. An advisor can
perform a check of the engine on
-board computer,
and 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. (Requires activation and an additional fee.)
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.

2-57
HomeLink
Transmitter
This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) this device may not cause harmful interference,
and (2) this device must accept any interference received
including interference that may cause undesired operation.
This device complies with RSS
-210 of Industry Canada.
Operation is subject to the following two conditions:
(1) this device may not cause interference, and (2) this
device must accept any interference, including interference
that may cause undesired operation of the device.
Changes and modifications to this system by other than
an authorized service facility could void authorization to
use this equipment.
Programming the HomeLink Transmitter
Do not use the HomeLink Transmitter with any garage
door opener that does not have the ªstop and reverseº
feature. This includes any garage door opener model
manufactured before April 1, 1982.
Be sure that people and objects are clear of the garage
door you are programming.
It is recommended that a new battery be installed in
your hand
-held transmitter for quicker and more
accurate transmission of the radio frequency.
Your vehicle's engine should be turned off while
programming the transmitter. Follow these steps to
program up to three channels:
1. Decide which one of the three channels (one of the
HomeLink buttons) you want to program.
2. Press and hold the desired button on HomeLink
through Step 3.
3. When the HomeLink indicator light begins to blink
slowly (this may take up to 30 seconds), hold the
hand
-held transmitter about 1 to 3 inches (3 to 8 cm)
away from HomeLink and then press and hold the
transmit button on the hand
-held transmitter.
Continue to hold both buttons until the indicator
light on HomeLink begins to flash rapidly
(this may take up to 90 seconds).

2-63 Speedometer and Odometer
Your speedometer lets you see your speed in both
miles per hour (mph) and kilometers per hour (km/h).
Your odometer shows how far your vehicle has been
driven, in either miles (used in the United States) or
kilometers (used in Canada).
Trip Odometer
The trip odometer can tell you how far your vehicle has
been driven since you last set the trip odometer to zero.
Press the reset button, located on the instrument panel
cluster next to the trip odometer display, to toggle
between the trip odometer and the regular odometer.
Holding the reset button for two seconds while the trip
odometer is displayed will reset it.
To display the odometer reading with the ignition off,
press the reset button.Engine Hour Meter Display
The odometer can also display the number of hours
the engine has run. To display the hour meter, turn the
ignition off, press and hold the reset button for at least
four seconds. The hour meter will be displayed for up to
30 seconds, or until the ignition is turned on.
Tachometer
Your tachometer displays the engine speed in
revolutions per minute (rpm).
NOTICE:
Damage to your engine or vehicle caused by
operating the engine in the red area isn't covered
by your vehicle warranty. Don't operate the
engine with the tachometer in the red area.

2-64
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 also has a message center 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 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 chime
nor the light will come on.

2-67
CAUTION:
If the air bag readiness light ever comes on when
you have turned off the air bag, it means that
something may be wrong with the air bag system.
The right front passenger's air bag could inflate
even though the switch is off.
If this ever happens, don't let anyone whom the
national government has identified as a member
of a passenger air bag risk group sit in the right
front passenger's position (for example, don't
secure a rear
-facing child restraint in the right
front passenger's seat) until you have your
vehicle serviced.
Voltmeter
United States Canada
When your engine is not running, but the ignition is in
RUN, this gage shows your battery's state of charge in
DC volts.

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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.
Readings in the low warning zone may occur when a
large number of electrical accessories are operating in
the vehicle and the engine is left at an idle for an
extended period. This condition is normal since the
charging system is not able to provide full power at idle
speed. As engine speeds are increased, this condition
should correct itself as higher engine speeds allow the
charging system to create maximum power.
You can only drive for a short time with the reading in
either warning zone. If you must drive, turn off all
unnecessary accessories.
Readings in either warning zone indicate a possible
problem in the electrical system. Have the vehicle
serviced as soon as possible.Brake System Warning Light
With the ignition on, the brake system warning light will
flash when you set the parking brake. The light will
flash if the parking brake doesn't release fully. If you
try to drive with the parking brake engaged, a chime
will sound when the vehicle speed is greater than
3 mph (5 km/h).
Your vehicle's hydraulic brake system is divided into
two parts. If one part isn't working, the other part can
still work and stop you. For good braking, though,
you need both parts working well.
If the warning light comes on, there could be a brake
problem. Have your brake system inspected right away.
United States Canada
This light should come on briefly when you turn the
ignition key to RUN. If it doesn't come on then, have it
fixed so it will be ready to warn you if there's a problem.

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If the light comes on while you are driving, pull off the
road and stop carefully. You may notice that the pedal is
harder to push. Or, the pedal may go closer to the floor.
It may take longer to stop. If the light is still on, have the
vehicle towed for service. See ªTowing Your Vehicleº in
the Index.
CAUTION:
Your brake system may not be working properly
if the brake system warning light is on. Driving
with the brake system warning light on can lead
to an accident. If the light is still on after you've
pulled off the road and stopped carefully, have
the vehicle towed for service.
Anti-Lock Brake System Warning Light
With the anti-lock brake
system, this light will
come on when you start
your engine and may stay
on for several seconds.
That's normal.
If the light stays on, or comes on when you're driving,
your vehicle needs service. If the regular brake system
warning light isn't on, you still have brakes, but you
don't have anti
-lock brakes. If the regular brake system
warning light is also on, you don't have anti
-lock brakes
and there's a problem with your regular brakes. See
ªBrake System Warning Lightº earlier in this section.
The anti
-lock brake system warning light should come
on briefly when you turn the ignition key to RUN.
If the light doesn't come on then, have it fixed so it
will be ready to warn you if there is a problem.