2005 GMC ENVOY XUV brakes

Towing a Trailer
{CAUTION:
If you do not use the correct equipment and
drive properly, you can lose control when you
pull a trailer. For example, if the trailer is too
heavy, the brakes may not work well — or even
at all. You and your passengers could be
seriously injured. You may also damage your
vehicle; the resulting repairs would not be
covered by your warranty. Pull a trailer only if
you have followed all the steps in this section.
Ask your dealer for advice and information
about towing a trailer with your vehicle.Notice:Pulling a trailer improperly can damage
your vehicle and result in costly repairs that would
not be covered by your warranty. Always follow
the instructions in this section and check with your
dealer for more information about towing a trailer
with your vehicle.
To identify what the vehicle trailering capacity is for your
vehicle, you should read the information in “Weight of
the Trailer” that appears later in this section.
Trailering is different than just driving your vehicle by
itself. Trailering means changes in acceleration, braking,
handling, durability and fuel economy. Successful,
safe trailering takes correct equipment, and it has to be
used properly.
That’s the reason for this part. In it are many time-tested,
important trailering tips and safety rules. Many of
these are important for your safety and that of your
passengers. So please read this section carefully before
you pull a trailer.
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If you will be pulling a trailer that, when loaded, will
weigh more than 4,000 lbs (1 814 kg) be sure to use a
properly mounted weight-distributing hitch and sway
control of the proper size. This equipment is very
important for proper vehicle loading and good handling
when driving. Always use a sway control if the trailer
will weigh more than these limits. You can ask a
hitch dealer about sway controls.
Safety Chains
You should always attach chains between your vehicle
and your trailer. Cross the safety chains under the
tongue of the trailer to help prevent the tongue from
contacting the road if it becomes separated from
the hitch. Instructions about safety chains may be
provided by the hitch manufacturer or by the
trailer manufacturer. Follow the manufacturer’s
recommendation for attaching safety chains and do not
attach them to the bumper. Always leave just enough
slack so you can turn with your rig. Never allow
safety chains to drag on the ground.
Trailer Brakes
If your trailer weighs more than 1,500 lbs (680 kg)
loaded, then it needs its own brakes — and they must
be adequate. Be sure to read and follow the instructions
for the trailer brakes so you’ll be able to install, adjust
and maintain them properly.
Your trailer’s brake system can tap into the vehicle’s
hydraulic brake system only if:
The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.
The trailer’s brake system will use less than
0.02 cubic inch (0.3 cc) of uid from your vehicle’s
master cylinder. Otherwise, both braking systems
won’t work well. You could even lose your brakes.
If everything checks out this far, then make the brake
uid tap at the port on the master cylinder that
sends uid to the rear brakes. But don’t use copper
tubing for this. If you do, it will bend and nally break off.
Use steel brake tubing.
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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 2-40.
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.
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 3-20.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.
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.
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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.
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.
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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 2-32.
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.
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Trailer Wiring Harness
Your vehicle may be equipped with a 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.)
Your vehicle is also 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.
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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...............................................5-6
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-7
Filling Your 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...................................................5-16
Engine Oil Life System..................................5-19
Engine Air Cleaner/Filter................................5-21
Automatic Transmission Fluid.........................5-22
Engine Coolant.............................................5-25
Radiator Pressure Cap..................................5-28
Engine Overheating.......................................5-28
Cooling System............................................5-30
Engine Fan Noise.........................................5-35
Power Steering Fluid.....................................5-36Windshield Washer Fluid................................5-37
Brakes........................................................5-38
Battery........................................................5-41
Jump Starting...............................................5-42
Rear Axle.......................................................5-47
Four-Wheel Drive............................................5-48
Front Axle......................................................5-49
Bulb Replacement..........................................5-50
Halogen Bulbs..............................................5-50
Headlamps, Front Turn Signal, and
Parking Lamps..........................................5-50
Taillamps, Turn Signal, and Stoplamps............5-51
Back-Up Lamps............................................5-52
Replacement Bulbs.......................................5-52
Windshield Wiper Blade Replacement..............5-53
Tires..............................................................5-55
Tire Sidewall Labelling...................................5-56
Tire Terminology and Denitions.....................5-59
Ination - Tire Pressure.................................5-61
Tire Inspection and Rotation...........................5-63
When It Is Time for New Tires.......................5-64
Buying New Tires.........................................5-65
Uniform Tire Quality Grading..........................5-66
Wheel Alignment and Tire Balance..................5-67
Section 5 Service and Appearance Care
5-1

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-21.
B. Engine Coolant Recovery Tank. SeeCooling System
on page 5-30.
C. Windshield Washer Fluid Reservoir. See “Adding
Washer Fluid” underWindshield Washer Fluid
on page 5-37.
D. Power Steering Fluid Reservoir. SeePower Steering
Fluid on page 5-36.
E. Automatic Transmission Fluid Dipstick (Out of View).
See “Checking the Fluid Level” underAutomatic
Transmission Fluid on page 5-22.
F. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil on page 5-16.G. Radiator Pressure Cap. SeeRadiator Pressure Cap
on page 5-28.
H. Engine Oil Fill Cap. See “When to Add Engine Oil”
underEngine Oil on page 5-16.
I. Remote Negative (−) Terminal (Marked GND). See
Jump Starting on page 5-42.
J. Brake Master Cylinder Reservoir. See “Brake Fluid”
underBrakes on page 5-38.
K. Battery. SeeBattery on page 5-41.
L. Engine Compartment Fuse Block. SeeEngine
Compartment Fuse Block on page 5-97.
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