sensor GMC ENVOY 1999 Owners Manual

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1-26

Air bags are designed to inflate only once. After they
inflate, you'll need some new parts for your air bag
system. If you don't get them, the air bag system
won't be there to help protect you in another crash.
A new system will include air bag modules and
possibly other parts. The service manual for your
vehicle covers the need to replace other parts.

Your vehicle is equipped with a diagnostic module,
which records information about the air bag system.
The module records information about the readiness
of the system, when the sensors are activated and
driver's safety belt usage at deployment.

Let only qualified technicians work on your air bag
system. Improper service can mean that your air bag
system won't work properly. See your dealer
for service.
NOTICE:
If you damage the covering for the driver's or the
right front passenger's air bag, the bag may not
work properly. You may have to replace the air
bag module in the steering wheel or both the air
bag module and the instrument panel for the
right front passenger's air bag. Do not open or
break the air bag coverings.
If your vehicle ever gets into a lot of water -- such as
water up to the carpeting or higher
-- or if water enters
your vehicle and soaks the carpet, the air bag controller
can be soaked and ruined. If this ever happens, and then
you start your vehicle, the damage could make the air bags
inflate, even if there's no crash. You would have to replace
the air bags as well as the sensors and related parts. If your
vehicle is ever in a flood, or if it's exposed to water that
soaks the carpet, you can avoid needless repair costs by
turning off the vehicle immediately and disconnecting the
battery cables. Don't let anyone start the vehicle under any
circumstances. See your dealer for service.
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1-27 Servicing Your Air Bag-Equipped Vehicle
Air bags affect how your vehicle should be serviced.
There are parts of the air bag system in several places
around your vehicle. You don't want the system to
inflate while someone is working on your vehicle. Your
dealer and the GM Service Manual have information
about servicing your vehicle and the air bag system. To
purchase a service manual, see ªService and Owner
Publicationsº in the Index.
CAUTION:
For up to two minutes after the ignition key is
turned off and the battery is disconnected, an air
bag can still inflate during improper service. You
can be injured if you are close to an air bag when
it inflates. Avoid wires wrapped with yellow tape
or yellow connectors. They are probably part of
the air bag system. Be sure to follow proper
service procedures, and make sure the person
performing work for you is qualified to do so.
The air bag system does not need regular maintenance.
Adding Equipment to Your Air
Bag-Equipped Vehicle
Q:If I add a push bumper or a bicycle rack to the
front of my vehicle, will it keep the air bags
from working properly?
A:As long as the push bumper or bicycle rack is
attached to your vehicle so that the vehicle's basic
structure isn't changed, it's not likely to keep the
air bags from working properly in a crash.
Q:Is there anything I might add to the front of the
vehicle that could keep the air bags from
working properly?
A:Yes. If you add things that change your vehicle's
frame, bumper system, front end sheet metal or
height, they may keep the air bag system from
working properly. Also, the air bag system may not
work properly if you relocate any of the air bag
sensors. If you have any questions about this, you
should contact Customer Assistance before you
modify your vehicle. (The phone numbers and
addresses for Customer Assistance are in Step Two of
the Customer Satisfaction Procedure in this manual.
See ªCustomer Satisfaction Procedureº in the Index.)
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2-40
Exterior Lamps
Your parking lamp and headlamp switch is on the
driver's side of your instrument panel.
Turn the knob clockwise to the parking lamps symbol to
manually turn on:

Parking Lamps

Sidemarker Lamps

Taillamps

License Plate Lamps

Instrument Panel LightsTurn the knob clockwise to the master lamps symbol to
turn on all the lamps listed as well as the headlamps.
Turn the knob all the way counterclockwise to turn off
your lamps and put the system in auto headlamp mode.
Automatic Headlamp System
When it is dark enough outside, your automatic
headlamp system will turn on your headlamps at the
normal brightness along with other lamps such as the
taillamps, sidemarker, parking lamps and the instrument
panel lights. The radio lights will also be dim.
Your vehicle is equipped with High Intensity Discharge
(HID) headlamps. Your headlamps come on at lower
intensity and gradually increase to full brightness.
Your vehicle is equipped with a light sensor on the top
of the instrument panel under the radio speaker grille.
Be sure it is not covered or the system will be on
whenever the ignition is on.
The system may also turn on your headlamps when
driving through a parking garage, heavy overcast
weather or a tunnel. This is normal.
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2-41
There is a delay in the transition between the daytime
and nighttime operation of the Daytime Running Lamps
(DRL) and the automatic headlamp systems so that
driving under bridges or bright overhead street lights
does not affect the system. The DRL and automatic
headlamp system will only be affected when the light
sensor sees a change in lighting lasting longer than
the delay.
To idle your vehicle with the automatic headlamp
system off, set the parking brake while the ignition is
off. Then start your vehicle. The automatic headlamp
system will stay off until you release the parking brake.
As with any vehicle, you should turn on the regular
headlamp system when you need it.
Lamps On Reminder
A reminder chime will sound when your headlamps or
parking lamps are manually turned on and your ignition
is in OFF, LOCK or ACCESSORY. To disable the
chime, turn the thumbwheel all the way down. In the
automatic mode, the headlamps turn off once the
ignition key is in OFF.
Daytime Running Lamps (If Equipped)
Daytime Running Lamps (DRL) can make it easier for
others to see the front of your vehicle during the day.
DRL can be helpful in many different driving
conditions, but they can be especially helpful in the
short periods after dawn and before sunset.
The DRL system will make your high
-beam headlamps
come on at reduced brightness when:

the ignition is on,

the headlamp switch is in automatic headlamp mode,

the light sensor detects daytime light,

the transmission is not in PARK (P), and

the parking brake is released.
When the DRL are on, only your high
-beam headlamps
will be on. The taillamps, sidemarker and other lamps
won't be on. The instrument panel won't be lit up either.
When it begins to get dark, the high
-beam headlamps
will automatically switch from DRL to the regular
low
-beam headlamps.
To idle your vehicle with the DRL off, put your
vehicle's transmission in PARK (P). The DRL will stay
off until you shift out of PARK (P).
As with any vehicle, you should turn on the regular
headlamp system when you need it.
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2-67 Air Bag Readiness Light
There is an air bag readiness light on the instrument
panel, which shows the air bag symbol. The system
checks the air bag's electrical system for malfunctions.
The light tells you if there is an electrical problem. The
system check includes the air bag sensors, the air bag
modules, the wiring and the crash sensing and
diagnostic module. For more information on the air bag
system, see ªAir Bagº in the Index.
This light will come on
when you start your engine,
and it will flash for a few
seconds. Then the light
should go out. This means
the system is ready.
If the air bag readiness light stays on after you start the
engine or comes on when you are driving, your air bag
system may not work properly. Have your vehicle
serviced right away.
The air bag readiness light should flash for a few
seconds 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.
Charging System Indicator Light
The charging system light
will come on briefly when
you turn on the ignition, but
the engine is not running, as
a check to show you it
is working.
It should go out once the engine is running. If it stays
on, or comes on while you are driving, you may have a
problem with the charging system. It could indicate that
you have problems with a generator drive belt, or
another electrical problem. Have it checked right away.
Driving while this light is on could drain your battery.
If you must drive a short distance with the light on, be
certain to turn off all your accessories, such as the radio
and air conditioner.
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3-3
Mode Knob - Automatic Operation
The right knob on the control panel allows you to
choose the direction of air delivery. When the system is
set for automatic operation, sensors will control the air
delivery mode. Air will come primarily from the floor or
instrument panel outlets, with some air directed to the
windshield to prevent fogging.
When the system is in AUTO mode, the air conditioning
light will turn on, and the recirculation and outside air
lights turn off. With the system in full auto control (both
the fan and mode knobs in AUTO), you still have the
ability to override any function. However, continually
overriding the outside air or the A/C compressor will limit
the ability of the system to cool the vehicle quickly.
If you push a button for a function which is not
available, the light next to that button will flash three
times to alert you that it's not available.
To find your comfort zone, start with the 74
F (23
C)
setting and allow about 20 minutes for the system to
adjust the temperature if necessary.
With the automatic setting, the air conditioning compressor
automatically cycles when needed to cool the air. In cold
weather, when the system senses the need for heat, the
airflow will be directed out the floor outlets. As the
interior temperature approaches the desired setting, theblower speed will decrease. To maintain interior comfort,
the airflow will adjust between the instrument panel air
outlets and floor outlets. On bright sunny days in cool
weather, the airflow may come out of the air conditioning
and floor outlets (bi
-level mode) to maintain comfort and
prevent stuffiness.
To avoid blowing cold air in cold weather, the system will
delay turning on the fan until warm air is available. The
length of delay depends on the outside air temperature,
engine coolant temperature or the time since the engine
was last started. As the coolant warms up, the blower fan
speed will gradually increase and air will flow from the
heater outlets, with some airflow to the windshield to
prevent fogging under most normal conditions.
If your vehicle is sitting out on a warm day and you
have the fan set on AUTO, the air will first flow out of
the floor air outlets for a few seconds. That is normal.
This is to expel hot air from the air outlets. As the air is
cooled, the airflow will move through the air
conditioning outlets.
Be careful not to put anything over the solar sensor
located around the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.
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6-57
Fuse/Circuit
BreakerUsage
14 Power Locks Motor
15 4WD Switch, Engine Controls
(VCM, PCM, Transmission)
16 Air Bag
17 Front Wiper
18 Steering Wheel Audio Controls
19 Radio, Battery
20 Amplifier
21 HVAC I (Automatic),
HVAC Sensors (Automatic)
22 Anti
-Lock Brakes
23 Rear Wiper
24 Radio, Ignition
Engine Compartment Fuse Block
The fuse block is under the hood at the driver's side of
the engine compartment.
Remove the cover by turning the fastener
counterclockwise. To reinstall the fuse panel cover, push
in and turn the fastener clockwise.
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Name Usage
TRL TRN Trailer Left Turn
TRR TRN Trailer Right Turn
TRL B/U Trailer Back
-Up Lamps
VEH B/U Vehicle Back
-Up Lamps
RT TURN Right Turn Signal FrontName Usage
LT TURN Left Turn Signal Front
LT TRN Left Turn Signal Rear
RT TRN Right Turn Signal Rear
RR PRK Right Rear Parking Lamps
TRL PRK Trailer Park Lamps
LT LOW Low
-Beam Headlamp, Left
RT LOW Low
-Beam Headlamp, Right
FRPRK Front Parking Lamps
INT BAT I/P Fuse Block Feed
ENG I Engine Sensors/Solenoids, MAF,
CAM, PURGE, VENT
ECM B Engine Control Module, Fuel
Pump, Module, Oil Pressure
ABS Anti
-Lock Brake System
ECM I Engine Control Module Injectors
A/C Air Conditioning
LT HI High
-Beam Headlamp, Left
RT HI High
-Beam Headlamp, Right
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6-59
Name Usage
HORN Horn
BTSI Brake
-Transmission
Shift Interlock
B/U LP Back
-Up Lamps
DRL Daytime Running Lamps
(If Equipped)
IGN B Column Feed, IGN 2, 3, 4
RAP Retained Accessory Power
LD LEV Electronic Load Leveling
OXYSEN Oxygen Sensor
MIR/LKS Mirrors, Door Locks
FOG LP Fog Lamps
IGN E Engine
IGN A Starting and Charging, IGN 1
STUD #2 Accessory Feeds, Electric Brake
PARKLP Parking Lamps
LR PRK Left Rear Parking LampsName Usage
IGN C Starter Solenoid, Fuel Pump,
PRNDL
HTDSEAT Heated Seats
HVAC HVAC System
TRCHMSL Trailer Center High
-Mounted
Stop Light
HIBEAM High
-Beam Headlamps
RRDFOG Rear Defogger
TBC Truck Body Computer
CRANK Clutch Switch, NSBU Switch
HAZLP Hazard Lamps
VECHMSL Vehicle Center High
-Mounted
Stop Lamp
HTDMIR Heated Mirror
ATC Automatic Transfer Case
STOPLP Stoplamps
RR W/W Rear Window Wiper
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