2004 GMC ENVOY towing

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

How to Inspect
To inspect the air cleaner/lter, remove the lter from
the vehicle and lightly shake lter to release loose dust
and dirt. If the lter remains “caked” with dirt, a new
lter is required.
To inspect or replace the lter, do the following:
1. Remove the screws on the engine cleaner/lter and
lift off the cover.
2. Remove the air cleaner/lter from the housing. Care
should be taken to dislodge as little dirt as possible.
3. Install the new engine air cleaner/lter.
4. Reinstall the cover and tighten the screws.
{CAUTION:
Operating the engine with the air cleaner/lter
off can cause you or others to be burned. The
air cleaner not only cleans the air, it helps to
stop ame if the engine backres. If it is not
there and the engine backres, you could
be burned. Do not drive with it off, and be
careful working on the engine with the air
cleaner/lter off.Notice:If the air cleaner/lter is off, a backre can
cause a damaging engine re. And, dirt can
easily get into your engine, which will damage it.
Always have the air cleaner/lter in place when you
are driving.
Automatic Transmission Fluid
When to Check and Change
A good time to check your automatic transmission uid
level is when the engine oil is changed.
Change both the uid and lter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the uid and lter every
100,000 miles (166 000 km).
5-22

6. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan.
7. By this time, the coolant level inside the radiator
ller neck may be lower. If the level is lower, add
more of the proper DEX-COOL
®coolant mixture
through the ller neck until the level reaches
the base of the ller neck.
8. Then replace the pressure cap. At any time during
this procedure if coolant begins to ow out of the
ller neck, reinstall the pressure cap. Be sure
the pressure cap is hand-tight.
Engine Fan Noise
This vehicle has a clutched engine cooling fan. When the
clutch is engaged, the fan spins faster to provide more air
to cool the engine. In most everyday driving conditions
the clutch is not engaged. This improves fuel economy
and reduces fan noise. Under heavy vehicle loading,
trailer towing, and/or high outside temperatures, the fan
speed increases when the clutch engages. So you may
hear an increase in fan noise. This is normal and should
not be mistaken as the transmission slipping or making
extra shifts. It is merely the cooling system functioning
properly. The fan will slow down when additional cooling
is not required and the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
5-36

(c)Visually inspect hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect all pipes,
ttings and clamps; replace with genuine GM parts as
needed. To help ensure proper operation, a pressure test
of the cooling system and pressure cap and cleaning the
outside of the radiator and air conditioning condenser is
recommended at least once a year.
(d)Visually inspect wiper blades for wear or cracking.
Replace blade inserts that appear worn or damaged
or that streak or miss areas of the windshield.
(e)Make sure the safety belt reminder light and all your
belts, buckles, latch plates, retractors and anchorages
are working properly. Look for any other loose or
damaged safety belt system parts. If you see anything
that might keep a safety belt system from doing its
job, have it repaired. Have any torn or frayed safety belts
replaced. Also look for any opened or broken air bag
coverings, and have them repaired or replaced. (The air
bag system does not need regular maintenance.)
(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
rear compartment hinges, outer liftgate handle pivot
points, rear door detent link, roller mechanism, liftgate
handle pivot points, latch bolt, fuel door hinge, cargo
door hinge, locks and folding seat hardware. More
frequent lubrication may be required when exposed to a
corrosive environment. Applying silicone grease on
weatherstrips with a clean cloth will make them
last longer, seal better and not stick or squeak.(g)Add uid as needed. A uid loss could indicate a
problem; repair as needed. Check vent hose at transfer
case for kinks and proper installation.
(h)Change automatic transmission uid and lter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police or delivery
service.
(i)Drain, ush and rell cooling system. See Engine
Coolant on page 5-25for what to use. Inspect hoses.
Clean radiator, condenser, pressure cap and ller neck.
Pressure test the cooling system and pressure cap.
(j)A uid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the uid level checked. Add uid if needed.
6-8

Climate Control System
Climate Controls Personalization....................3-31
Dual..........................................................3-20
Dual Automatic............................................3-24
Rear..........................................................3-28
Compass Calibration.......................................2-36
Compass Operation.........................................2-36
Compass Variance..........................................2-37
Content Theft-Deferrent....................................2-17
Control of a Vehicle.......................................... 4-5
Convenience Net............................................2-50
Coolant
Engine Temperature Gage............................3-39
Heater, Engine............................................2-23
Cooling System..............................................5-30
Cruise Control................................................3-12
Cruise Control Light........................................3-46
CURB VIEW ACTIVATED.................................3-62
Current and Past Model Order Forms................7-13
Customer Assistance Information
Courtesy Transportation.................................. 7-7
Customer Assistance for Text
Telephone (TTY) Users............................... 7-4
Customer Assistance Offices........................... 7-4
Customer Satisfaction Procedure..................... 7-2
GM Mobility Program for Persons
with Disabilities.......................................... 7-5
Reporting Safety Defects to General Motors....7-11Customer Assistance Information (cont.)
Reporting Safety Defects to
the Canadian Government.........................7-11
Reporting Safety Defects to
the United States Government...................7-11
Roadside Assistance Program......................... 7-6
Service Publications Ordering Information........7-12
D
Daytime Running Lamps (DRL).........................3-16
Defensive Driving............................................. 4-2
Defogging and Defrosting.........................3-22, 3-26
Delayed Locking............................................... 2-9
Dinghy Towing................................................4-45
Doing Your Own Service Work........................... 5-3
Dolly Towing..................................................4-47
Dome Lamp Override......................................3-18
Dome Lamps.................................................3-18
Door
Delayed Locking........................................... 2-9
Locks.......................................................... 2-8
Power Door Locks......................................... 2-9
Programmable Automatic Door Locks.............2-10
Rear Door Security Locks.............................2-13
4

Maintenance Schedule (cont.)
Owner Checks and Services........................... 6-9
Recommended Fluids and Lubricants.............6-12
Scheduled Maintenance................................. 6-4
Using Your................................................... 6-3
Your Vehicle and the Environment................... 6-2
Maintenance When Trailer Towing.....................4-65
Making Turns.................................................4-62
Malfunction Indicator Light................................3-40
Matching Transmitter(s) to Your Vehicle............... 2-6
Memory Seat.................................................2-52
Message
DIC Warnings and Messages........................3-59
Mexico, Central America and Caribbean
Islands/Countries (Except Puerto Rico and
U.S. Virgin Islands)....................................... 7-5
Mirror Operation.............................................2-36
Mirrors
Automatic Dimming Rearview with OnStar
®
and Compass..........................................2-36
Outside Automatic Dimming Mirror with Curb
View Assist.............................................2-39
Outside Convex Mirror.................................2-39
Outside Heated Mirrors................................2-39
Outside Manual Mirrors................................2-38
Outside Power Mirrors..................................2-38
MyGMLink.com................................................ 7-3
N
Navigation/Radio System................................3-103
New Vehicle Break-In......................................2-19
Normal Maintenance Replacement Parts............6-14
O
Odometer......................................................3-34
Off-Road Recovery..........................................4-12
Oil
Change Engine Oil Light...............................3-45
Engine.......................................................5-16
Pressure Gage............................................3-44
OIL PRESSURE LOW/STOP ENGINE...............3-60
Older Children, Restraints................................1-29
Online Owner Center........................................ 7-3
OnStar
®Personal Calling.................................2-41
OnStar®Services............................................2-40
OnStar®System.............................................2-40
OnStar®Virtual Advisor....................................2-41
Operating Your All-Wheel-Drive Vehicle Off
Paved Roads..............................................4-15
Other Warning Devices...................................... 3-6
Outlet Adjustment...................................3-23, 3-27
10

R
Radiator Pressure Cap....................................5-27
Radio Data System (RDS)...............3-64, 3-76, 3-90
Radio Messages.....................................3-70, 3-81
Radios..........................................................3-63
Care of Your Cassette Tape Player...............3-118
Care of Your CD and DVD Player................3-119
Care of Your CDs and DVDs.......................3-119
Navigation/Radio System.............................3-103
Radio Personalization.................................3-115
Radio with Cassette and CD.........................3-75
Radio with CD............................................3-64
Radio with Six-Disc CD................................3-90
Rear Seat Audio........................................3-114
Setting the Time..........................................3-63
Theft-Deterrent..........................................3-116
Understanding Reception............................3-117
Rainsense™ Wipers........................................3-10
RDS Messages..............................3-69, 3-80, 3-94
Reading Lamps..............................................3-18
REAR ACCESS OPEN....................................3-61
Rear Axle......................................................5-49
Locking......................................................4-10
Rear Climate Control System............................3-28
Rear Compartment Storage Panel/Cover............2-48Rear Door Security Locks................................2-13
Rear Floor Storage Lid....................................2-50
Rear Safety Belt Comfort Guides......................1-25
Rear Seat Audio (RSA)..................................3-114
Rear Seat Entertainment System.....................3-104
Rear Seat Operation......................................... 1-5
Rear Seat Passenger Positions.........................1-22
Rear Seat Passengers, Safety Belts..................1-22
Rear Seats (Envoy XL)..................................... 1-7
Rear Storage Area..........................................2-48
Rear Underseat Fuse Block............................5-109
Rear Window Defogger............................3-22, 3-27
Rearview Mirror, Automatic Dimming with
OnStar
®and Compass.................................2-36
Reclining Seatbacks, Power............................... 1-4
Recommended Fluids and Lubricants.................6-12
Recreational Vehicle Towing.............................4-44
Reduced Engine Power Light............................3-46
Remote Control.............................................3-107
Remote Keyless Entry System............................ 2-5
Remote Keyless Entry System, Operation............ 2-6
Removing the Flat Tire and
Installing the Spare Tire................................5-83
Removing the Spare Tire and Tools...................5-77
Replacement Bulbs.........................................5-54
Replacing Brake System Parts..........................5-42
12

Towing
Recreational Vehicle.....................................4-44
Towing a Trailer..........................................4-55
Your Vehicle...............................................4-43
Traction
Assist System (TAS)...................................... 4-8
Trailer Brakes.................................................4-60
Trailer Wiring Harness.....................................4-66
Transfer Case................................................5-50
Transmission
Fluid, Automatic...........................................5-22
Transmission Operation, Automatic....................2-24
Transmission, Transaxle, Transfer Case Unit
Repair Manual............................................7-12
Transportation Options...................................... 7-8
Travel Note Recorder......................................2-46
Traveling to Remote Areas...............................4-17
Trip Information..............................................3-51
Trip Odometer................................................3-34
Turn and Lane Change Signals.......................... 3-8
TURN SIGNAL ON.........................................3-60
Turn Signal/Multifunction Lever........................... 3-7
Turn Signals When Towing a Trailer..................4-63
Two-Wheel-Drive Vehicles................................4-45U
Understanding Radio Reception.......................3-117
Uniform Tire Quality Grading............................5-69
United States................................................... 7-4
Used Replacement Wheels..............................5-72
Using Cleaner on Fabric..................................5-92
Using HomeLink
®...........................................2-44
Using Song List Mode...................................3-101
V
Vehicle
Control........................................................ 4-5
Damage Warnings........................................... iv
Loading......................................................4-48
Symbols......................................................... iv
Vehicle Data Collection and Event Data Records....7-10
Vehicle Identication
Number (VIN).............................................5-99
Service Parts Identication Label..................5-100
Vehicle Personalization
Memory Seat..............................................2-52
16