2005 GMC ENVOY Owner's Manual

Driving with a Trailer
{CAUTION:
If you have a rear-most window open and you
pull a trailer with your vehicle, carbon
monoxide (CO) could come into your vehicle.
You can not see or smell CO. It can cause
unconsciousness or death. SeeEngine
Exhaust on page 2-34. To maximize your safety
when towing a trailer:
Have your exhaust system inspected for
leaks and make necessary repairs before
starting on your trip.
Keep the rear-most windows closed.
CAUTION: (Continued)
CAUTION: (Continued)

If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main heating
or cooling system on and with the fan on
any speed. This will bring fresh, outside air
into your vehicle. Do not use the climate
control setting for maximum air because it
only recirculates the air inside your vehicle.
SeeDual Climate Control System on
page 3-21orDual Automatic Climate
Control System on page 3-23.
Towing a trailer requires a certain amount of experience.
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the trailer.
And always keep in mind that the vehicle you are
driving is now a good deal longer and not nearly as
responsive as your vehicle is by itself.
4-63

Before you start, check all trailer hitch parts and
attachments, safety chains, electrical connection, lamps,
tires and mirror adjustment. If the trailer has electric
brakes, start your vehicle and trailer moving and then
apply the trailer brake controller by hand to be sure
the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer
brakes are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving your vehicle without a trailer.
This can help you avoid situations that require
heavy braking and sudden turns.
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.
4-64

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

Parking on Hills
{CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But if you ever have to park your rig on a hill, here’s
how to do it:
1. Apply your regular brakes, but don’t shift into
PARK (P) yet. When parking uphill, turn your wheels
away from the curb. When parking downhill, turn
your wheels into the curb.
2. Have someone place chocks under
the trailer wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake, and then shift into PARK (P).
5. Release the regular brakes.
{CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
If you have left the engine running, the vehicle
can move suddenly. You or others could be
injured. To be sure your vehicle will not move,
even when you are on fairly level ground, use
the steps that follow.
Always put the shift lever fully in PARK (P) with
the parking brake rmly set.
If the transfer case on four-wheel drive vehicles
is in NEUTRAL, your vehicle will be free to roll,
even if your shift lever is in PARK (P). So, be
sure the transfer case is in a drive gear — not in
NEUTRAL.
SeeFour-Wheel Drive on page 2-26.
4-66

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

Service............................................................5-3
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside
of Your Vehicle...........................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-5
Gasoline Specications....................................5-5
California Fuel...............................................5-5
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-6
Filling Your Tank............................................5-7
Filling a Portable Fuel Container.......................5-9
Checking Things Under the Hood....................5-10
Hood Release..............................................5-10
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-16
Engine Oil Life System..................................5-19
Engine Air Cleaner/Filter................................5-20
Automatic Transmission Fluid.........................5-22
Engine Coolant.............................................5-25
Radiator Pressure Cap..................................5-28
Engine Overheating.......................................5-28
Cooling System............................................5-30Engine Fan Noise.........................................5-35
Power Steering Fluid.....................................5-36
Windshield Washer Fluid................................5-36
Brakes........................................................5-37
Battery........................................................5-41
Jump Starting...............................................5-42
Rear Axle.......................................................5-47
Four-Wheel Drive............................................5-48
Front Axle......................................................5-48
Bulb Replacement..........................................5-49
Halogen Bulbs..............................................5-49
Headlamps, Front Turn Signal, Sidemarker,
and Parking Lamps....................................5-50
Taillamps, Turn Signal, and Stoplamps............5-50
Back-Up Lamps............................................5-51
Replacement Bulbs.......................................5-51
Windshield Wiper Blade Replacement..............5-52
Tires..............................................................5-54
Tire Sidewall Labelling...................................5-55
Tire Terminology and Denitions.....................5-58
Ination - Tire Pressure.................................5-61
Tire Inspection and Rotation...........................5-62
When It Is Time for New Tires.......................5-64
Section 5 Service and Appearance Care
5-1

Buying New Tires.........................................5-64
Uniform Tire Quality Grading..........................5-65
Wheel Alignment and Tire Balance..................5-66
Wheel Replacement......................................5-67
Tire Chains..................................................5-68
Accessory Inator.........................................5-69
If a Tire Goes Flat........................................5-70
Changing a Flat Tire.....................................5-71
Removing the Spare Tire and Tools................5-72
Removing the Flat Tire and Installing
the Spare Tire..........................................5-75
Secondary Latch System...............................5-80
Storing a Flat or Spare Tire and Tools............5-82
Spare Tire...................................................5-85
Appearance Care............................................5-86
Fabric/Carpet...............................................5-86
Vinyl...........................................................5-88
Leather.......................................................5-88
Instrument Panel..........................................5-88
Interior Plastic Components............................5-88
Glass Surfaces.............................................5-88
Care of Safety Belts......................................5-89
Weatherstrips...............................................5-89Washing Your Vehicle...................................5-89
Cleaning Exterior Lamps/Lenses.....................5-90
Finish Care..................................................5-90
Windshield, Backglass, and Wiper Blades.........5-91
Aluminum Wheels.........................................5-91
Tires...........................................................5-92
Sheet Metal Damage.....................................5-92
Finish Damage.............................................5-93
Underbody Maintenance................................5-93
Chemical Paint Spotting.................................5-93
Vehicle Care/Appearance Materials..................5-94
Vehicle Identication......................................5-95
Vehicle Identication Number (VIN).................5-95
Service Parts Identication Label.....................5-95
Electrical System............................................5-96
Add-On Electrical Equipment..........................5-96
Headlamps..................................................5-96
Windshield Wiper Fuses................................5-96
Power Windows and Other Power Options.......5-96
Fuses and Circuit Breakers............................5-97
Engine Compartment Fuse Block....................5-97
Rear Underseat Fuse Block..........................5-106
Capacities and Specications........................5-113
Section 5 Service and Appearance Care
5-2