trailer GMC SIERRA 2005 Service Manual

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.
Fifth Wheel and Gooseneck Trailering
Fifth wheel and gooseneck trailers can be used
with many pickup models. These trailers place a
larger percentage of the weight (kingpin weight)
on the tow vehicle than conventional trailers. Make
sure this weight does not cause the vehicle to
exceed GAWR or GVWR.
Fifth wheel or gooseneck kingpin weight should be
15 to 25 percent of the trailer weight up to the maximum
amount specied in the trailering chart for your vehicle.
See “Weight of the Trailer” in this section for more
information.The hitch should be located in the pickup bed so that its
centerline is over or slightly in front of the rear axle.
Take care that it is not so far forward that it will contact
the back of the cab in sharp turns. This is especially
important for short box pickups. Trailer pin box
extensions and sliding fth wheel hitch assemblies can
help this condition. There should be at least
six inches of clearance between the top of the pickup
box and the bottom of the trailer shelf that extends over
the box.
Make sure the hitch is attached to the tow vehicle frame
rails. Do not use the pickup box for support.
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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. If you are towing a trailer up to 5,000 lbs
(2 271 kg) with a factory-installed step bumper, you
may attach the safety chains to the attaching points on
the bumper. If you are towing a trailer up to your
vehicle’s trailer rating limit you may attach the safety
chains to the attaching point on the hitch platform. If you
are towing with an aftermarket hitch follow the trailer
or hitch manufacturer’s recommendation for attaching
safety chains. 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 2,000 lbs (900 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 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, make the brake tap at
the port on the master cylinder that sends the 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 cannot see or smell CO. It can cause
unconsciousness or death. SeeEngine
Exhaust on page 2-53. 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. SeeClimate Control System
on page 3-21.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 connector, 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.
While towing a trailer or when exposed to long periods
of sunshine, the oor of the truck bed may become
very warm. Avoid putting items in the truck bed
that might be affected by high ambient temperatures.
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.
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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.
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.
If you have an automatic transmission, you can tow in
DRIVE (D). You may want to shift the transmission
to a lower gear selection if the transmission shifts too
often (e.g., under heavy loads and/or hilly conditions).
You may also want to activate the tow/haul mode if
the transmission shifts too often. SeeTow/Haul Mode
Light on page 3-49.
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If you have a 5-speed manual transmission and you are
towing a trailer, it’s better not to use FIFTH (5) gear.
Just drive in FOURTH (4) gear (or, as you need
to, a lower gear).
If you have a 6-speed manual transmission and you are
towing a trailer, it’s better not to use SIXTH (6) gear.
Drive in FIFTH (5) gear (or, as you need to, a lower
gear).
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. For manual
transmissions, let the engine run while parked,
preferably on level ground, with the transmission out of
gear and the parking brake applied, for a few minutes
before turning the engine off. If you do get the overheat
warning, seeEngine Overheating on page 5-37.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 for an automatic transmission, or into
gear for a manual transmission.
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 shift into PARK (P) for an
automatic transmission, or REVERSE (R) for a
manual transmission.
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5. If you have a four-wheel-drive vehicle, be sure the
transfer case is in a drive gear and not in
NEUTRAL.
6. 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.
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
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.
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Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling a trailer. SeeScheduled Maintenance on
page 6-4for more information. Things that are especially
important in trailer operation are automatic transmission
uid (don’t overll), engine oil, axle lubricant, belt,
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.
Trailer Wiring Harness
Your vehicle is equipped with one of the following wiring
harnesses for towing a trailer or hauling a slide-in
camper.
Basic Trailer Wiring
All regular, extended cab and crew cab pickups have an
eight-wire trailer towing harness.For vehicles not equipped with heavy duty trailering, the
harness is clipped to the vehicle’s frame behind the
spare tire mount. The harness requires the installation
of a trailer connector, which is available through
your dealer.
If your trailer is equipped with electric brakes, you can
get a jumper harness (electric trailer brake control)
with a trailer battery feed fuse from your dealer.
If you need to tow a light-duty trailer with a standard
four-way round pin connector, you can also get an
adapter form your dealer.
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Heavy-DutyTrailer Wiring Harness
Package
For vehicles equipped with heavy duty trailering, the
harness is connected to the trailer plug mounted to the
hitch platform.The eight-wire harness contains the following trailer
circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Light Blue: CHMSL*
Red: Battery Feed**
Dark Blue: Trailer Brake
* The Center High-Mounted Stoplamp (CHMSL) wire is
tied next to the trailer wiring harness for use with a
trailer, slide-in camper or cap.
**If your vehicle is charging a remote (non-vehicle)
battery, turn on the headlamps to boost the vehicle
system voltage and properly charge the battery.
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Camper/Fifth-Wheel Trailer Wiring Package
The eight-wire camper harness is located under the
front edge of the pickup box on the driver’s side of the
vehicle, attached to the frame bracket. A connector
will have to be added to the wiring harness which
connects to the camper.
The eight-wire harness contains the following
camper/trailer circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Light Blue: Center High-Mounted Stoplamp
(CHMSL)
Red: Battery Feed
Dark Blue: Trailer BrakeIf your vehicle is equipped with the “Heavy-Duty
Trailering” option, please refer to “Heavy-Duty Trailer
Wiring Package” earlier in this section.
When the camper-wiring harness is ordered without the
heavy-duty trailering package, an eight-wire harness
with a seven-pin connector and separate CHMSL
connector are located at the rear of the vehicle and are
tied to the vehicle’s frame.
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Electric Brake Control Jumper
{CAUTION:
Be sure to use only the correct trailer brake
harness, the one intended for use on your
vehicle. If you use some other trailer brake
harness, even if it seems to t, your trailer
brakes may not work at all. You could have a
crash in which you or others could be injured.
Use only the trailer brake harness intended for
your vehicle. If it is no longer available to you,
be sure to get a proper replacement from
your dealer.This harness is included with your vehicle as part of the
heavy-duty trailer wiring package.
This harness is for an electric brake controller and
includes a trailer battery feed fuse. It should be installed
by your dealer or a qualied service center.
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