1999 GMC SONOMA Security light on

2-10 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 chime 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
If you park in a lot where someone will be watching
your vehicle, it's 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.
Content Theft-Deterrent
(If Equipped)
Your vehicle may be equipped with a Content
Theft
-Deterrent alarm system.
With this system, the
SECURITY light will flash
as you open the door
(if your ignition is off).
This light 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
light should come on and stay on.

2-11
3. Close all doors. The SECURITY light should go off
after approximately 30 seconds. The alarm is not
armed until the SECURITY light goes off.
If a door is opened without the key or the remote keyless
entry transmitter, the alarm will go off. Your vehicle's
headlamps will flash and the horn will sound for
110 seconds, then will turn off to save the battery power.
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.
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 locked.

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 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. The alarm won't stop if
you try to unlock a door any other way.
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 light 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.

2-12
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 will go off approximately
five seconds after the key is turned to the
RUN ignition position.
If the engine stalls and the SECURITY light flashes,
wait about 10 minutes 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 does not start after three (3) tries, the
vehicle needs service.
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 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.
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.

2-65 Security Warning Light
This light will come on
briefly when you turn the
key toward START. The
light will stay on until the
engine starts.
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 dealer.
Also see ªContent Theft
-Deterrentº in the Index for
additional information regarding the SECURITY light.
Service Four-Wheel-Drive Warning Light
If your vehicle is equipped with the Automatic
Four
-Wheel-Drive Transfer Case, it has a computer
which controls the four
-wheel-drive system.
This light should come on
briefly when you turn on the
ignition, as a check to show
you it is working.
The SERVICE 4WD light comes on to indicate that
there may be a problem with the four
-wheel-drive
system and service is required. Malfunctions can be
indicated by the system before any problem is apparent,
which may prevent serious damage to the vehicle. This
system is also designed to assist your service technician
in correctly diagnosing a malfunction.