2004 GMC ENVOY Owner's Manual

Adding a Snow Plow or Similar
Equipment
Your vehicle was neither designed nor intended for a
snow plow.
Notice:Adding a snow plow or similar equipment
to your vehicle can damage it, and the repairs would
not be covered by warranty. Do not install a snow
plow or similar equipment on your vehicle.
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. 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 the trailering capacity of 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 Do Decide To Pull A Trailer
If you do, here are some important points:
There are many different laws, including speed limit
restrictions, having to do with trailering. Make sure
your rig will be legal, not only where you live
but also where you’ll be driving. A good source for
this information can be state or provincial police.
Consider using a sway control. See “Hitches” later
in this section.
Don’t tow a trailer at all during the rst 500 miles
(800 km) your new vehicle is driven. Your engine,
axle or other parts could be damaged.
Then, during the rst 500 miles (800 km) that you
tow a trailer, don’t drive over 50 mph (80 km/h)
and don’t make starts at full throttle. This helps your
engine and other parts of your vehicle wear in at
the heavier loads.
You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or, if necessary, a
lower gear selection if the transmission shifts
too often (e.g., under heavy loads and/or hilly
conditions).Three important considerations have to do with weight:
the weight of the trailer,
the weight of the trailer tongue
and the weight on your vehicle’s tires.
Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to pull
a trailer are all important. And, it can also depend
on any special equipment that you have on your vehicle.
Look in the following chart to nd the maximum trailer
weight for your vehicle.
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Vehicle Axle Ratio Max.Trailer Wt. *GCWR
2WD Envoy (L6 Engine)3.42 5,300 lbs. (2 404 kg) 10,000 lbs. (4 536 kg)
3.73 5,700 lbs. (2 585 kg) 10,500 lbs. (4 763 kg)
4.10 6,200 lbs. (2 812 kg) 11,000 lbs. (4 990 kg)
4WD Envoy (L6 Engine)3.42 5,100 lbs. (2 313 kg) 10,000 lbs. (4 536 kg)
3.73 5,500 lbs. (2 495 kg) 10,500 lbs. (4 763 kg)
4.10 6,100 lbs. (2 767 kg) 11,000 lbs. (4 990 kg)
2WD Envoy XL (L6 Engine)3.42 5,000 lbs. (2 268 kg) 10,000 lbs. (4 536 kg)
3.73 5,500 lbs. (2 495 kg) 10,500 lbs. (4 763 kg)
4.10 6,000 lbs. (2 722 kg) 11,000 lbs. (4 990 kg)
4WD Envoy XL (L6 Engine)3.42 4,800 lbs. (2 177 kg) 10,000 lbs. (4 536 kg)
3.73 5,300 lbs. (2 404 kg) 10,500 lbs. (4 763 kg)
4.10 5,800 lbs. (2 631 kg) 11,000 lbs. (4 990 kg)
2WD Envoy XL (V8 Engine)3.42 5,900 lbs. (2 676 kg) 11,000 lbs. (4 990 kg)
3.73 6,800 lbs. (3 084 kg) 12,500 lbs. (5 670 kg)
4WD Envoy XL (V8 Engine)3.42 5,700 lbs. (2 585 kg) 11,000 lbs. (4 990 kg)
3.73 6,300 lbs. (2 858 kg) 12,500 lbs. (5 670 kg)
*The Gross Combination Weight Rating (GCWR) is the
total allowable weight of the completely loaded
vehicle and trailer including any passengers, cargo,
equipment and conversion. The GCWR for your vehicle
should not be exceeded.
You can ask your dealer for our trailering information or
advice, or you can write us at the address listed in your
Warranty and Owner Assistance Information Booklet.In Canada, write to:
General Motors of Canada Limited
Customer Communication Centre, 163-005
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7
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Weight of the Trailer Tongue
The tongue load (A) of any trailer is an important weight
to measure because it affects the total or gross weight
of your vehicle. The Gross Vehicle Weight (GVW)
includes the curb weight of the vehicle, any cargo you
may carry in it, and the people who will be riding in
the vehicle. If you have a lot of options, equipment,
passengers or cargo in your vehicle, it will reduce the
tongue weight your vehicle can carry, which will
also reduce the trailer weight your vehicle can tow. And
if you will tow a trailer, you must add the tongue load
to the GVW because your vehicle will be carrying
that weight, too. See Loading Your Vehicle for more
information about your vehicle’s maximum load capacity.
The trailer tongue weight (A) should be 10 percent to
15 percent of the total loaded trailer weight (B), up to a
maximum of 400 lbs. (181 kg) with a weight carrying
hitch. The trailer tongue weight (A) should be 10 percent
to 15 percent of the total loaded trailer weight (A), up
to a maximum of 900 lbs. (408 kg) for a weight
distributing hitch.
Do not exceed the maximum allowable tongue weight
for your vehicle. Choose the shortest hitch extension
that will position the hitch ball closest to the vehicle. This
will help reduce the effect of trailer tongue weight on
the rear axle.
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After you’ve loaded your trailer, weigh the trailer and
then the tongue, separately, to see if the weights
are proper. If they aren’t, you may be able to get them
right simply by moving some items around in the
trailer.
Total Weight on Your Vehicle’s Tires
Be sure your vehicle’s tires are inated to the upper limit
for cold tires. You’ll nd these numbers on the
Certication label at the rear edge of the driver’s door or
see Loading Your Vehicle for more information. Then,
be sure you don’t go over the GVW limit for your vehicle,
or the GAWR, including the weight of the trailer
tongue. If you use a weight distributing hitch, make sure
you don’t go over the rear axle limit before you apply
the weight distribution spring bars.
Hitches
It’s important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads are
a few reasons why you’ll need the right hitch.
Weight Distributing Hitches and Weight
Carrying Hitches
When using a weight-distributing hitch, the hitch must
be adjusted so the distance (A) remains the same both
before and after coupling the trailer to the tow vehicle.
If you use a step-bumper hitch, the bumper could
be damaged in sharp turns. Make sure there is ample
room when turning to avoid contact between the
trailer and the bumper.(A) Body to Ground Distance, (B) Front of Vehicle
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If you will be pulling a trailer that, when loaded, will
weigh more than 5,000 lbs (2 270 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 2-34. 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.
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. See Climate Control System
in the Index.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 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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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.
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