2005 GMC ENVOY wiring

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 cannot
see or smell CO. It can cause
unconsciousness and even death. If you must
drive with the liftgate 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 and select the
control setting that will force outside air
into your vehicle. See Climate Control
System in the Index.
If you have air outlets on or under the
instrument panel, open them all the way.
SeeEngine Exhaust on page 2-34.
Liftgate Release
To unlock the liftgate, you may use the power door
locks or the keyless entry system described earlier.
On some vehicles the liftglass will also unlock when the
liftgate is unlocked. Press the pushbutton on the
liftglass to open it.
To open the entire liftgate, lift the handle located in the
center of the liftgate. If you open the liftgate, the
liftgate module will lock the liftglass after a one to
two second delay.
Emergency Release for
Opening Liftgate
1. Remove the trim plug to expose the access hole in
the trim panel. The access hole is located on the
inside of the liftgate in the center.
2. Use a tool to reach through the access hole in the
trim panel.
3. Pry the left release lever up to the unlock position.
Pry the right release lever up to unlatch the liftgate.
4. Reattach the trim plug.
2-13

If a bulb is burned out, replace it to help avoid an
accident. If the arrows don’t go on at all when you signal
a turn, check the fuse. SeeFuses and Circuit Breakers
on page 5-97and check for burned-out bulbs.
If you have a trailer towing option with added wiring for
the trailer lamps, a different turn signal asher is
used. With this asher installed, the signal indicator will
ash even if a turn signal bulb is burned out. Check
the front and rear turn signal lamps regularly to make
sure they are working.
Turn Signal On Chime
If your turn signal is left on for more than 3/4 of a mile
(1.2 km), a chime will sound at each ash of the
turn signal. To turn off the chime, move the turn signal
lever to the off position.
Headlamp High/Low-Beam Changer
To change the headlamps from low to high beam,
push the lever toward the instrument panel. To return to
low-beam headlamps, pull the multifunction lever
toward you. Then release it.When the high beams are
on, this indicator light on
the instrument panel
cluster will also be on.
Flash-to-Pass
This feature lets you use your high-beam headlamps
to signal a driver in front of you that you want to pass.
It works even if your headlamps are in the
automatic position.
To use it, pull the turn signal lever toward you, then
release it.
If your headlamps are in the automatic position or on low
beam, your high-beam headlamps will turn on. They’ll
stay on as long as you hold the lever toward you. The
high-beam indicator on the instrument panel cluster will
come on. Release the lever to return to normal operation.
3-8

Airbag Readiness Light
There is an airbag readiness light on the instrument
panel, which shows the airbag symbol. The system
checks the airbag’s electrical system for malfunctions.
The light tells you if there is an electrical problem.
The system check includes the airbag sensors, the
airbag modules, the wiring and the crash sensing and
diagnostic module. For more information on the
airbag system, seeAirbag System on page 1-48.
This light will come on
when you start your
vehicle, and it will ash for
a few seconds. Then the
light should go out. This
means the system is ready.
If the airbag readiness light stays on after you start the
vehicle or comes on when you are driving, your
airbag system may not work properly. Have your vehicle
serviced right away.{CAUTION:
If the airbag readiness light stays on after you
start your vehicle, it means the airbag system
may not be working properly. The airbags in
your vehicle may not inate in a crash, or they
could even inate without a crash. To help avoid
injury to yourself or others, have your vehicle
serviced right away if the airbag readiness light
stays on after you start your vehicle.
The airbag readiness light should ash for a few
seconds when you turn the ignition key to RUN. If the
light doesn’t come on then, have it xed so it will
be ready to warn you if there is a problem.
3-36

Trailer Wiring Harness
Your vehicle may be equipped with the seven-wire
trailer towing harness. This harness has a seven-pin
universal heavy-duty trailer connector that is attached
to a bracket on the hitch platform. The seven-wire
harness contains the following trailer circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Running Lamps
White: Ground
Light Green: Back-up Lamps
Dark Blue: Electric Brakes
Red: Battery Feed (The chassis wiring ring terminal
must be fastened to a stud on the underhood
electrical center before the trailer feed will
become active.)
If you need to tow a light-duty trailer with a standard
four-way round pin connector, an adapter connector is
available from your dealer.
Your vehicle may also be equipped with wiring for an
electric trailer brake controller. These wires are located
inside the vehicle on the driver’s side under the
instrument panel. These wires should be connected to
an electric trailer brake controller by your dealer or
a qualied service center.
4-68

Headlamps, Front Turn Signal,
Sidemarker, and Parking Lamps
To replace a headlamp, front turn signal/parking or
sidemarker bulb, do the following:
1. Open the hood.Hood Release on page 5-10for
more information.
2. Lift the inner quick release clips.
3. Pull the headlamp assembly away from the vehicle.
4. Remove the cover from the headlamp bulb.
5. Disconnect the wiring harness.
6. Remove the bulb that needs to be replaced by
turning the socket counterclockwise.
7. Replace the old bulb with a new one.
8. Reinstall by reversing Steps 1 through 6.
Taillamps, Turn Signal, and
Stoplamps
To replace a stoplamp/taillamp or turn signal bulb, do
the following:
1. Open the liftgate. SeeLiftgate/Liftglass on
page 2-13for more information.
2. Remove the two
screws from the
taillamp assembly.
3. Pull the assembly away from the vehicle.
5-50

4. Unclip the wiring harness (A) and remove the
three socket retaining screws (B).
5. Remove the socket by releasing the retaining tabs.
6. Holding the socket, pull the bulb to release it from
the socket.
7. Push the new bulb into the socket until it clicks.
8. Reinstall the socket and screws.
9. Reconnect the wiring harness.
10. Reinstall the taillamp assembly and tighten
the screws.
11. Close the liftgate.
Back-Up Lamps
The back-up lamps are located in the rear bumper.
To replace a bulb, do the following:
1. Reach behind the rear bumper and locate
the bulb socket.
2. Turn it counterclockwise to remove from the bulb
assembly.
3. Pull the bulb from the bulb socket.
4. Push in a new bulb into the bulb socket.
5. Reinstall the bulb socket by lining up the tabs in the
lamp assembly and turn it clockwise to secure it.
Replacement Bulbs
Exterior Lamp Bulb Number
Back-up Lamps 3157
Front Sidemarker Lamps 194
Front Turn Signal Lamps 3457
Halogen Headlamps
High-Beam 9005 HB3
Low-Beam 9006 HB4
Rear Turn Signal, Stoplamp and
Taillamp3057
For replacement bulbs not listed here, contact
your dealer.
5-51

Electrical System
Add-On Electrical Equipment
Notice:Don’t add anything electrical to your
vehicle unless you check with your dealer rst.
Some electrical equipment can damage your vehicle
and the damage wouldn’t be covered by your
warranty. Some add-on electrical equipment can
keep other components from working as
they should.
Your vehicle has an airbag system. Before attempting to
add anything electrical to your vehicle, seeServicing
Your Airbag-Equipped Vehicle on page 1-62.
Headlamps
The headlamp wiring is protected by four fuses.
An electrical overload will cause a lamp to go on and
off. If this happens, have your headlamp wiring checked
right away.
Windshield Wiper Fuses
The windshield wiper motor is protected by a circuit
breaker and a fuse. If the motor overheats due to heavy
snow or ice, the wiper will stop until the motor cools.
If the overload is caused by some electrical problem,
be sure to get it xed.
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 xed or goes away.
5-96

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 res
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.
Engine Compartment Fuse Block
The fuse block is located under the hood in the engine
compartment on the driver’s side of the vehicle. See
Engine Compartment Overview on page 5-12for more
information on location.
Remove the primary cover by pressing the two locking
tabs. Remove the secondary cover by snapping off
while lifting. To reinstall the fuse panel cover, reverse
the sequence.
5-97