2002 GMC SIERRA ECU

2-11 Tailgate Removal
The tailgate on your vehicle can be removed to allow for
different loading situations. Although the tailgate can be
removed without assistance, you may want someone to
assist you with the removal to avoid possible damage to
the vehicle.
To remove the tailgate, do the following:
1. Raise the tailgate
slightly and release
both retaining cable
clips. To release the
retaining cable clips,
lift the cable so that it
points straight out;
then, push the cable
clip forward.
2. With the tailgate at a
slightly upward angle,
pull back on the tailgate
at the right edge and
then move the tailgate to
the right to release the
left edge.
Reverse the procedure to reinstall the tailgate.
Make sure it is secure.

2-13
Content Theft-Deterrent
Your vehicle is equipped with a content theft-deterrent
alarm system. You can disable the system or personalize
it to suit your needs. See ªSecondary Information
Centerº in the Index for more information.
With this system,
the SECURITY message
on the cluster will flash
as you open the door
(if your ignition is off).
This message reminds you to activate the theft
-deterrent
system. Here's how to do it:
1. Open the door.
2. Lock the door with the power door lock switch or the
remote keyless entry transmitter. The SECURITY
message should come on and stay on. If you are
using the remote keyless entry transmitter, the door
does not need to be open.3. Close all of the doors. The SECURITY message
should go off after approximately 15 seconds.
The alarm is not armed until the SECURITY
message goes off.
Once the system is armed, if a door is opened without the
key or the remote keyless entry transmitter, the alarm will
go off. Depending on how you have programmed the
alarm in the secondary information center, the horn may
sound, the headlamps may flash or both the headlamps
and the horn will activate. See ªSecondary Information
Centerº in the Index for more information.
Remember, the theft
-deterrent system won't activate if
you lock the doors with a key or use the manual door
lock. It activates only if you use a power door lock
switch with the door open, or with the remote keyless
entry transmitter. You should also remember that you
can start your vehicle with the correct ignition key if the
alarm has been set off.

2-14
Here's how to avoid setting off the alarm by accident:

If you don't want to activate the theft
-deterrent
system, the vehicle should be locked with the door
key after the doors are closed.

Always unlock a door with a key, or use the remote
keyless entry transmitter. Unlocking a door any
other way will set off the alarm if the system has
been armed.
If you set off the alarm by accident, unlock any door
with the key. You can also turn off the alarm by pressing
UNLOCK on the remote keyless entry transmitter or by
placing the key in the ignition and turning it to START.
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 and the headlamps
do not flash, you may have the feature turned off.
See ªSecondary Information Centerº in the Index for
more information.

2-15
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 message 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 GMC Roadside Assistance
Center. See ªRoadside Assistanceº in the Index.
New Vehicle ªBreak-Inº
NOTICE:
Your vehicle doesn't need an elaborate
ªbreak
-in.º But it will perform better in
the long run if you follow these guidelines:

Keep your speed at 55 mph (88 km/h) or
less for the first 500 miles (805 km).

Don't drive at any one speed
-- fast or
slow
-- for the first 500 miles (805 km).
Don't make full
-throttle starts.

Avoid making hard stops for the first
200 miles (322 km) or so. During this time
your new brake linings aren't yet broken
in. Hard stops with new linings can mean
premature wear and earlier replacement.
Follow this breaking
-in guideline every
time you get new brake linings.

Don't tow a trailer during break
-in.
See ªTowing a Trailerº in the Index for
more information.

2-55
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.

2-56
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.
Route Support: An advisor can provide directions or
guidance to most places you want to go. In addition,
they can help you locate gas stations, rest areas, ATMs,
hospitals, hotels, stores, eateries and more.
Ride Assist: An advisor can locate transportation in the
event that you are unable to drive.
Concierge Services: The concierge advisor can obtain
tickets, reservations or help with vacation/trip planning
and other unique items and services.
OnStar System Limitations
Complete limitations can be found on the subscriber
services agreement. In order to provide you with
excellent service, calls with the OnStar Center may be
monitored or recorded.OnStar Service is:

available in the 48 contiguous United States, Alaska,
Hawaii and Canada;

available when the vehicle is within the operating
range of a cellular provider;

subject to limitations caused by atmospheric
conditions, such as severe weather or topographical
conditions, such as mountainous terrain.

subject to cellular carrier equipment limitations.
Global positioning locating capabilities will not be
available if satellite signals are obstructed.
OnStar will not function if the vehicle's battery is
discharged or disconnected. It may also be inoperative
if the vehicle is in an accident and the OnStar or vehicle
electrical system components are damaged.
OnStar is the communication link between you and
existing governmental emergency and roadside service
providers. OnStar will receive your call and use
reasonable effort to contact an appropriate provider.
OnStar cannot promise that the providers will respond
in a timely manner or at all.

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.

2-80 Check Eng Oil Pressure
This message is displayed
when the engine oil pressure
is low.
See ªOil Pressure Gageº in the Index for more information.
Check Eng Oil Level
This message is displayed
when the engine oil level
is low.
Once oil is added, it may need time to drain and settle in
the engine before this message will turn off. It is best to
let the engine cool down (if it is hot) or warm up (if it is
cold) and cycle the ignition to be sure this message turns
off. Refer to the dipstick for the correct level.
See ªEngine Oilº in the Index on how to check the oil
level and for what type of oil to add.
Change Engine Oil
This message is displayed
when the engine oil
needs to be changed.
The message is only
displayed for 15 seconds
at the start of each
ignition cycle.
When you change the engine oil, be sure to reset the
CHANGE ENGINE OIL message. See ªEngine Oil,
When to Changeº in the Index.
Security
This message is displayed
when the content
theft
-deterrent system
has been activated and
also monitors the
Passlock

system.
If the security message is displayed 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.