2005 GMC ENVOY towing

Turn Signals When Towing a Trailer
The arrows on your instrument panel will ash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will also ash, telling other drivers
you’re about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will ash 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.
Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you don’t shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.You can tow in DRIVE (D). You may want to shift the
transmission to THIRD (3) or a lower gear, under heavy
loads or hilly conditions.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If you turn your
engine off immediately after towing at high altitude on
steep uphill grades, your vehicle may show signs similar
to engine overheating. To avoid this, let the engine run
while parked (preferably on level ground) with the
automatic transmission in PARK (P) for a few minutes
before turning the engine off. If you do get the overheat
warning, seeEngine Overheating on page 5-28.
4-65

When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
start your engine,
shift into a gear, and
release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store
the chocks.
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 uid (don’t overll),
engine oil, axle lubricant, belt(s), cooling system and
brake system. Each of these is covered in this manual,
and the Index will help you nd 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.
4-67

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

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).
How to Check
Because this operation can be a little difficult,
you may choose to have this done at the dealership
service department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
part or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.
Wait at least 30 minutes before checking the
transmission uid level if you have been driving:
When outside temperatures are above 90°F (32°C).
At high speed for quite a while.
In heavy traffic — especially in hot weather.
While pulling a trailer.
To get the right reading, the uid should be at normal
operating temperature, which is 180°F to 200°F
(82°C to 93°C).
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
Your 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.
5-35

(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 airbag
coverings, and have them repaired or replaced.
(The airbag 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)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. This service
can be complex; you should have your dealer perform
this service. See Engine Coolant on page 5-25 for
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.
(k)If you drive regularly under dusty conditions, inspect
the lter at each engine oil change.
6-8

Q
Questions and Answers About Safety Belts.........1-13
R
Radiator Pressure Cap....................................5-28
Radios..........................................................3-65
Care of Your Cassette Tape Player...............3-137
Care of Your CD and DVD Player................3-139
Care of Your CDs and DVDs.......................3-138
Navigation/Radio System.............................3-134
Radio with Cassette and CD.........................3-93
Radio with CD....................................3-66, 3-77
Radio with Six-Disc CD..............................3-107
Rear Seat Audio........................................3-134
Setting the Time..........................................3-65
Theft-Deterrent..........................................3-135
Understanding Reception............................3-137
Rainsense™ Wipers.......................................... 3-9
Reading Lamps..............................................3-19
Rear Axle......................................................5-47
Locking......................................................4-11
Rear Climate Control System............................3-28
Rear Compartment Storage Panel/Cover............2-56
Rear Door Security Locks................................2-12
Rear Floor Storage Lid....................................2-58
Rear Safety Belt Comfort Guides......................1-23Rear Seat Audio (RSA)..................................3-134
Rear Seat Entertainment System.....................3-121
Rear Seat Operation......................................... 1-5
Rear Seat Passengers, Safety Belts..................1-21
Rearview Mirror with Compass..........................2-36
Rearview Mirror with Compass and Temperature........
2-41, 3-35
Rearview Mirror with OnStar®...........................2-36
Rearview Mirror with OnStar®and Compass.......2-39
Rearview Mirror with OnStar®, Compass, and
Temperature Display....................................2-43
Rearview Mirrors.............................................2-36
Reclining Seatbacks.......................................... 1-3
Recommended Fluids and Lubricants.................6-12
Recreational Vehicle Towing.............................4-51
Reduced Engine Power Light............................3-47
Remote Keyless Entry System............................ 2-5
Remote Keyless Entry System, Operation............ 2-6
Removing the Flat Tire and Installing the
Spare Tire..................................................5-75
Removing the Spare Tire and Tools...................5-72
Replacement Bulbs.........................................5-51
Reporting Safety Defects
Canadian Government..................................7-12
General Motors...........................................7-13
United States Government............................7-12
Restraint System Check
Checking Your Restraint Systems...................1-64
10

Tires (cont.)
Tire Terminology and Denitions....................5-58
Uniform Tire Quality Grading.........................5-65
Wheel Alignment and Tire Balance.................5-66
Wheel Replacement.....................................5-67
When It Is Time for New Tires......................5-64
Top Strap......................................................1-35
Top Strap Anchor Location...............................1-37
Towing
Recreational Vehicle.....................................4-51
Towing a Trailer..........................................4-56
Your Vehicle...............................................4-51
Traction
Assist System (TAS)...................................... 4-9
Transmission
Fluid, Automatic...........................................5-22
Transmission Operation, Automatic....................2-23
Trip Odometer................................................3-34
Turn and Lane-Change Signals.......................... 3-7
Turn Signal/Multifunction Lever........................... 3-7U
Understanding Radio Reception.......................3-137
Uniform Tire Quality Grading............................5-65
V
Vehicle
Control........................................................ 4-6
Damage Warnings........................................... iv
Symbols......................................................... iv
Vehicle Customization, DIC..............................3-59
Vehicle Data Collection and Event Data
Recorders..................................................7-10
Vehicle Identication
Number (VIN).............................................5-95
Service Parts Identication Label...................5-95
Vehicle Personalization
Memory Seat..............................................2-60
Ventilation Adjustment......................................3-28
Visors...........................................................2-16
Voltmeter Gage..............................................3-39
13