2004 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 can not
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.
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.
2-14

Turn and Lane Change Signals
The turn signal has two upward (for right) and two
downward (for left) positions. These positions allow you
to signal a turn or a lane change.
To signal a turn, move the lever all the way up or down.
When the turn is nished, the lever will return
automatically.
An arrow on the instrument
panel cluster will ash in
the direction of the
turn or lane change.
To signal a lane change, just raise or lower the lever
until the arrow starts to ash. Hold it there until you
complete your lane change. The lever will return by itself
when you release it. The bottom of the outside
rearview mirrors may also be equipped with lane change
indicators.As you signal a turn or a lane change, if the arrows
ash more quickly than normal, a signal bulb may
be burned out and other drivers won’t see your turn
signal.
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 5-101and 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.
3-8

Tachometer
The tachometer displays the engine speed in revolutions
per minute (rpm).
Notice:If you operate the engine with the
tachometer in the shaded warning area, your vehicle
could be damaged, and the damages would not
be covered by your warranty. Do not operate
the engine with the tachometer in the shaded
warning area.
Safety Belt Reminder Light
When the key is turned to RUN, a chime will come on
for several seconds to remind people to fasten their
safety belts, unless the driver’s safety belt is already
buckled.
The safety belt light will
also come on and stay on
for several seconds, then it
will ash for several more.
If the driver’s belt is already buckled, neither the chime
nor the light will come on.
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, seeAir Bag Systems on page 1-51.
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.
3-35

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
Red: Battery Feed
Dark Blue: Electric Brakes
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.
4-66

Bulb Replacement
For the type of bulbs, seeReplacement Bulbs on
page 5-54.
For any bulb changing procedure not listed in this
section, contact your dealer.
Halogen Bulbs
{CAUTION:
Halogen bulbs have pressurized gas inside
and can burst if you drop or scratch the bulb.
You or others could be injured. Be sure to read
and follow the instructions on the bulb
package.
Headlamps
1. Open the hood.
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 headlamp bulb by turning the socket
counterclockwise.
7. To install the replacement bulb, reverse Steps 1
through 6.
Front Turn Signal and Sidemarker
Lamps
Follow the same procedure listed for headlamp removal
earlier in this section. Replace the turn signal or
sidemarker bulb instead.
Taillamps and Turn Signal Lamps
1. Open the liftgate.
5-52

2. Remove the two
screws from the lamp
assembly.
3. Pull the assembly away from the vehicle.
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 lamp assembly and tighten the
screws.
11. Close the liftgate.
5-53

Engine Identication
The 8th character in your VIN is the engine code. This
code will help you identify your engine, specications
and replacement parts.
Service Parts Identication Label
You’ll nd this label on the inside of the glove box.
It’s very helpful if you ever need to order parts. On this
label is:
your VIN,
the model designation,
paint information and
a list of all production options and special
equipment.
Be sure that this label is not removed from the vehicle.
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 air bag system. Before attempting
to add anything electrical to your vehicle, see
Servicing Your Air Bag-Equipped Vehicle on page 1-61.
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.
5-100

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.
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.
5-101