2009 GMC ENVOY Owner's Manual

Driving with a Trailer
{CAUTION:
When towing a trailer, exhaust gases may collect
at the rear of the vehicle and enter if the liftgate,
trunk/hatch, or rear-most window is open.
Engine exhaust contains carbon monoxide (CO)
which cannot be seen or smelled. It can cause
unconsciousness and even death.
To maximize safety when towing a trailer:
Have the exhaust system inspected for leaks
and make necessary repairs before starting
a trip.
Never drive with the liftgate, trunk/hatch, or
rear-most window open.
Fully open the air outlets on or under the
instrument panel.
Adjust the Climate Control system to a setting
that brings in only outside air and set the fan
speed to the highest setting. See Climate
Control System in the Index.
For more information about carbon monoxide, see
Engine Exhaust on page 2-37.Towing a trailer requires a certain amount of experience.
Get to know the rig before setting out for the open road.
Get acquainted 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 longer and not as
responsive as the vehicle is by itself.
Before starting, check all trailer hitch parts and
attachments, safety chains, electrical connectors, lamps,
tires and mirror adjustments. If the trailer has electric
brakes, start the vehicle and trailer moving and then
apply the trailer brake controller by hand to be sure the
brakes are working. This checks the electrical connection
at the same time.
During the 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 the vehicle without a trailer.
This can help to avoid situations that require heavy
braking and sudden turns.
Passing
More passing distance is needed when towing a trailer.
Because the rig is longer, it is necessary to go much
farther beyond the passed vehicle before returning to
the lane.
4-53

Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, 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. The vehicle could be damaged. Avoid
making very sharp turns while trailering.
When turning with a trailer, make wider turns than
normal. Do this so the trailer will not strike soft shoulders,
curbs, road signs, trees or other objects. Avoid jerky or
sudden maneuvers. Signal well in advance.
Turn Signals When Towing a Trailer
The arrows on the instrument panel ash whenever
signaling a turn or lane change. Properly hooked up, the
trailer lamps also ash, telling other drivers the vehicle
is turning, changing lanes or stopping.When towing a trailer, the arrows on the instrument
panel ash for turns even if the bulbs on the trailer are
burned out. For this reason you may think other
drivers are seeing the signal when they are not. It is
important to check occasionally to be sure the
trailer bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbeforestarting
down a long or steep downgrade. If the transmission is
not shifted down, the brakes might have to be used so
much that they would get hot and no longer work well.
Vehicles can tow in D (Drive). Shift the transmission to
a lower gear if the transmission shifts too often under
heavy loads and/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 the engine is
turned off immediately after towing at high altitude
on steep uphill grades, the vehicle may show signs
similar to engine overheating. To avoid this, let
the engine run while parked, preferably on level ground,
with the transmission in P (Park) for a few minutes
before turning the engine off. If the overheat warning
comes on, seeEngine Overheating on page 5-30.
4-54

Parking on Hills
{CAUTION:
Parking the vehicle on a hill with the trailer attached
can be dangerous. If something goes wrong, the rig
could start to move. People can be injured, and
both the vehicle and the trailer can be damaged.
When possible, always park the rig on a at
surface.
If parking the rig on a hill:
1. Press the brake pedal, but do not shift into P (Park)
yet. Turn the wheels into the curb if facing downhill
or into traffic if facing uphill.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
brake pedal until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking
brake and shift into P (Park).
5. Release the brake pedal.
{CAUTION:
It can be dangerous to get out of the vehicle if the
shift lever is not fully in P (Park) with the parking
brake rmly set. The vehicle can roll.
If the engine has been left running, the vehicle can
move suddenly. You or others could be injured. To
be sure the vehicle will not move, even when on
fairly level ground, use the steps that follow.
Always put the shift lever fully in P (Park) with the
parking brake rmly set.
If the transfer case on four-wheel drive vehicles is
in N (Neutral), the vehicle will be free to roll, even
if the shift lever is in P (Park). Be sure the transfer
case is in a drive gear — not in N (Neutral).
SeeFour-Wheel Drive on page 2-28.
4-55

Leaving After Parking on a Hill
1. Apply and hold the brake pedal while you:
start the 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
The vehicle needs service more often when pulling a
trailer. See this manual’s Maintenance Schedule
or Index for more information. Things that are especially
important in trailer operation are automatic transmission
uid, engine oil, axle lubricant, belts, cooling system
and brake system. It is a good idea to inspect
these before and during the trip.
Check periodically to see that all hitch nuts and bolts
are tight.
Trailer Wiring Harness
The vehicle may have a seven-wire trailer towing
harness. This harness may have a seven-pin universal
heavy-duty trailer connector (if equipped with the
trailering package) that is attached to a bracket on
the hitch platform or included with the four-pin trailer
towing harness. If the vehicle is not equipped with the
heavy-duty trailer connector, one may be purchased from
your dealer/retailer.
4-56

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 BrakesIf towing a light-duty trailer with a standard four-way
round pin connector, an adapter connector is available
from your dealer/retailer.
If charging a remote (non-vehicle) battery, turn on the
headlamps to boost the vehicle system voltage and
properly charge the battery.
The vehicle is also equipped with wiring for an
electric trailer brake controller. These wires are
located inside the vehicle on the driver side under the
instrument panel. These wires should be connected
to an electric trailer brake controller by your
dealer/retailer or a qualied service center.
4-57

✍NOTES
4-58

Service............................................................5-3
Accessories and Modications..........................5-3
California Proposition 65 Warning.....................5-4
California Perchlorate Materials Requirements.....5-4
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside of the
Vehicle......................................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-5
Gasoline Specications....................................5-6
California Fuel...............................................5-6
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-7
Filling the Tank..............................................5-8
Filling a Portable Fuel Container.....................5-10
Checking Things Under the Hood....................5-10
Hood Release..............................................5-11
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-15
Engine Oil Life System..................................5-18
Engine Air Cleaner/Filter................................5-20
Automatic Transmission Fluid.........................5-21
Cooling System............................................5-24
Engine Coolant.............................................5-25
Engine Overheating.......................................5-30
Engine Fan Noise.........................................5-32Power Steering Fluid.....................................5-33
Windshield Washer Fluid................................5-34
Brakes........................................................5-35
Battery........................................................5-38
Jump Starting...............................................5-39
Rear Axle.......................................................5-43
Four-Wheel Drive............................................5-44
Front Axle......................................................5-44
Headlamp Aiming
...........................................5-45
Bulb Replacement..........................................5-46
Halogen Bulbs..............................................5-46
Headlamps..................................................5-46
Front Turn Signal, Sidemarker and
Parking Lamps..........................................5-47
Taillamps, Turn Signal, and Stoplamps............5-47
Back-Up Lamps............................................5-48
License Plate Lamp......................................5-49
Replacement Bulbs.......................................5-49
Windshield Wiper Blade Replacement..............5-50
Tires..............................................................5-53
Tire Sidewall Labeling...................................5-54
Tire Terminology and Denitions.....................5-57
Ination - Tire Pressure.................................5-60
High-Speed Operation...................................5-62
Tire Pressure Monitor System.........................5-63
Section 5 Service and Appearance Care
5-1

Tire Pressure Monitor Operation.....................5-64
Tire Inspection and Rotation...........................5-68
When It Is Time for New Tires.......................5-69
Buying New Tires.........................................5-70
Different Size Tires and Wheels......................5-72
Uniform Tire Quality Grading..........................5-72
Wheel Alignment and Tire Balance..................5-74
Wheel Replacement......................................5-74
Tire Chains..................................................5-76
If a Tire Goes Flat........................................5-76
Tire Sealant and Compressor Kit....................5-77
Tire Sealant and Compressor Kit Storage.........5-87
Changing a Flat Tire.....................................5-88
Removing the Spare Tire and Tools................5-89
Removing the Flat Tire and Installing the
Spare Tire................................................5-92
Secondary Latch System...............................5-97
Storing a Flat or Spare Tire and Tools...........5-100
Spare Tire.................................................5-102
Appearance Care..........................................5-103
Interior Cleaning.........................................5-103
Fabric/Carpet..............................................5-104
Leather......................................................5-105
Instrument Panel, Vinyl, and Other Plastic
Surfaces.................................................5-106Care of Safety Belts....................................5-106
Weatherstrips.............................................5-106
Washing Your Vehicle..................................5-107
Cleaning Exterior Lamps/Lenses....................5-107
Finish Care................................................5-108
Windshield, Backglass, and Wiper Blades.......5-108
Aluminum Wheels.......................................5-109
Tires.........................................................5-109
Sheet Metal Damage...................................5-109
Finish Damage...........................................5-110
Underbody Maintenance...............................5-110
Chemical Paint Spotting...............................5-110
Vehicle Identication.....................................5-111
Vehicle Identication Number (VIN)................5-111
Service Parts Identication Label...................5-111
Electrical System..........................................5-112
Add-On Electrical Equipment.........................5-112
Headlamps.................................................5-112
Windshield Wiper Fuses...............................5-112
Power Windows and Other Power Options......5-112
Fuses and Circuit Breakers..........................5-113
Engine Compartment Fuse Block...................5-113
Rear Underseat Fuse Block..........................5-116
Capacities and Specications........................5-120
Section 5 Service and Appearance Care
5-2