1999 GMC ENVOY wiring

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2-9
Liftgate/Liftglass
CAUTION:
It can be dangerous to drive with the liftgate or
liftglass open because carbon monoxide (CO) gas
can come into your vehicle. You can't see or smell
CO. It can cause unconsciousness and even death.
If you must drive with the liftgate or liftglass
open or if electrical wiring or other cable
connections must pass through the seal between
the body and the liftgate or liftglass:

Make sure all other windows are shut.

Turn the fan on your heating or cooling
system to its highest speed with the setting
on any airflow selection except
RECIRCULATION. That will force outside
air into your vehicle. See ªComfort
Controlsº in the Index.

If you have air outlets on or under the
instrument panel, open them all the way.
See ªEngine Exhaustº in the Index.
Liftgate Release
To release the liftgate or liftglass, you may use your
power door locks or the keyless entry system
described earlier.
The liftglass can be opened
using the pushbutton on the
liftgate after the driver's
door has been opened using
either the power lock
system or the keyless
entry system.
To open the entire liftgate, unlock the doors using either
the power door lock system or the remote keyless entry
system and lift the handle located in the center of
the liftgate.
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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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4-51 Passing
You'll need more passing distance up ahead when
you're towing a trailer. And, because you're a good deal
longer, you'll need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that hand
to the left. To move the trailer to the right, move your
hand to the right. Always back up slowly and, if
possible, have someone guide you.
Making Turns
NOTICE:
Making very sharp turns while trailering could
cause the trailer to come in contact with the
vehicle. Your vehicle could be damaged. Avoid
making very sharp turns while trailering.
When you're turning with a trailer, make wider turns than
normal. Do this so your trailer won't strike soft shoulders,
curbs, road signs, trees or other objects. Avoid jerky or
sudden maneuvers. Signal well in advance.
Turn Signals When Towing a Trailer
When you tow a trailer, your vehicle has to have extra
wiring and a heavy
-duty turn signal flasher.
The arrows on your instrument panel will flash
whenever you signal a turn or lane change. Properly
hooked up, the trailer lamps will also flash, telling other
drivers you're about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will flash for turns even if the bulbs on the trailer
are burned out. Thus, you may think drivers behind you
are seeing your signal when they are not. It's important
to check occasionally to be sure the trailer bulbs are
still working.
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4-54 Maintenance When Trailer Towing
Your vehicle will need service more often when you're
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission fluid (don't
overfill), engine oil, axle lubricant, belt, cooling system
and brake system. Each of these is covered in this
manual, and the Index will help you find them quickly.
If you're trailering, it's a good idea to review these
sections before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
Trailer Wiring Harness
The heavy-duty trailer wiring is an eight-wire harness
assembly. The harness is stored under the vehicle, on the
driver's side corner frame rear crossmember. The
heavy
-duty trailer wiring has a 30-amp feed wire with
an in
-line fuse located by the junction block. See ªFuses
and Circuit Breakersº in the Index. The harness does not
have a connector and should be wired by a qualified
electrical technician. The technician can use the
following color code chart when connecting the wiring
harness to your trailer.

Dark Blue: Use for electric trailer brakes or
auxiliary wiring.
Red: Use for battery charging; it connects to the
starter solenoid.

Light Green: Back
-up lamps.

Brown: Taillamps and parking lamps.

Yellow: Left stoplamp and turn signal.

Dark Green: Right stoplamp and turn signal.

White (Heavy Gauge): Ground wire.

White (Light Gauge): Auxiliary stoplamp.
Securely attach the harness to the trailer, then tape or
strap it to your vehicle's frame rail. Be sure you leave it
loose enough so the wiring doesn't bend or break, but
not so loose that it drags on the ground. Store the
harness in its original place. Wrap the harness together
and tie it neatly so it won't be damaged.
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6-55 Windshield Wipers
The windshield wiper motor is protected by a circuit
breaker and a fuse. If the motor overheats due to heavy
snow or ice, the wipers will stop until the motor cools. If
the overload is caused by some electrical problem, be
sure to get it fixed.
Power Windows and Other Power Options
Circuit breakers protect the power windows and other
power accessories. When the current load is too heavy,
the circuit breaker opens and closes, protecting the
circuit until the problem is fixed or goes away.
Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses and circuit
breakers. This greatly reduces the chance of fires caused
by electrical problems.
Look at the silver
-colored band inside the fuse. If the
band is broken or melted, replace the fuse. Be sure you
replace a bad fuse with a new one of the identical size
and rating.If you ever have a problem on the road and don't have a
spare fuse, you can borrow one that has the same
amperage. Just pick some feature of your vehicle that
you can get along without
-- like the radio or cigarette
lighter
-- and use its fuse, if it is the correct amperage.
Replace it as soon as you can.
Instrument Panel Fuse Block
The instrument panel fuse
block is at the driver's end
of the instrument panel.
Remove the cover by turning the fastener
counterclockwise. Extra fuses and the fuse extractor are
provided in the cover. To reinstall the fuse panel cover,
push in and turn the fastener clockwise.
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9-9
Speech Impaired, Customer Assistance 8-4 . . . . . . . . . . . . . . .
Speedometer 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stains, Cleaning 6-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starter Switch Check 7-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your Engine 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Steam 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Steering
In Emergencies 4
-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Steering Wheel, Tilt 2-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Compartments 2-46 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage, Vehicle 6-31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storing a Flat or Spare Tire and Tools 5-28 . . . . . . . . . . . . . . .
Stuck: In Sand, Mud, Ice or Snow 5-30 . . . . . . . . . . . . . . . . . .
Sun Visors 2-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sunglasses Storage 2-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sunroof 2-58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Symbols, Vehicle v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tachometer 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Taillamp Bulb Replacement 6-34 . . . . . . . . . . . . . . . . . . . . . . .
Tape Player Care 3-25, 7-39 . . . . . . . . . . . . . . . . . . . . . . . . . .
Theft 2-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
THEFTLOCK
3-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat 6-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Third Gear 2-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tilt Steering Wheel 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Time, Setting 3-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tire Chains 6-45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tire Inflation Check 7-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tires
Alignment and Balance 6
-43 . . . . . . . . . . . . . . . . . . . . . . . .
Buying New 6-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing a Flat 5-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cleaning 6
-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inflation 6-38, 7-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Rotation 6-39 . . . . . . . . . . . . . . . . . . . . . . . .
Pressure 6-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature 6-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Traction 6-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Treadwear 6-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Uniform Quality Grading 6-42 . . . . . . . . . . . . . . . . . . . . . . .
Wear Indicators 6-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When It's Time for New 6-40 . . . . . . . . . . . . . . . . . . . . . . .
Top Strap 1-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Torque Lock 2-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Torque, Wheel Nut 5-27, 6-60 . . . . . . . . . . . . . . . . . . . . . . . . .
Tow/Haul
Mode 4
-46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mode Light 2-75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selector Switch 2-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Towing a Trailer 4-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Towing, Recreational Vehicle 4-39 . . . . . . . . . . . . . . . . . . . . .
Towing Your Vehicle 5-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Trailer
Brakes 4
-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving on Grades 4-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving with a Trailer 4-50 . . . . . . . . . . . . . . . . . . . . . . . . . .
Hitches 4-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance When Towing 4-54 . . . . . . . . . . . . . . . . . . . . .
Parking on Hills 4-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Safety Chains 4-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tongue Weight 4-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Total Weight on Tires 4-48 . . . . . . . . . . . . . . . . . . . . . . . . . .
Towing 4-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turn Signals 4-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Weight 4-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring Harness 4-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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