engine GMC SIERRA 2000 Repair Manual

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4-57
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.
Tow/Haul Mode (If Equipped)
Tow/haul is a feature on automatic transmission
equipped vehicles that assists when pulling a heavy
trailer or a large or heavy load. The purpose of the
tow/haul mode is to:

Reduce the frequency and improve the predictability
of transmission shifts when pulling a heavy trailer or
a large or heavy load.

Provide the same solid shift feel when pulling a
heavy trailer or a large or heavy load as when the
vehicle is unloaded.

Improve control of vehicle speed while requiring less
throttle pedal activity when pulling a heavy trailer or
a large or heavy load.
Automatic transmission equipped vehicles are provided
with a button at the end of the shift lever which when
pressed enables tow/haul. When the button is pressed,
a light on the instrument panel will illuminate to
indicate that tow/haul has been selected. Tow/haul may be turned off by pressing the button
again, at which time the indicator light on the instrument
panel will turn off. The vehicle will automatically turn
off tow/haul every time it is started.
Tow/haul is designed to be most effective when the
vehicle and trailer combined weight is at least 75% of
the vehicle's Gross Combined Weight Rating (GCWR).
Tow/haul is most useful under the following
driving conditions:

When pulling a heavy trailer or a large or heavy load
through rolling terrain.

When pulling a heavy trailer or a large or heavy load
in stop and go traffic.

When pulling a heavy trailer or a large or heavy load
in busy parking lots where improved low speed
control of the vehicle is desired.
Operating the vehicle in tow/haul when lightly loaded or
with no trailer at all will not cause damage. However,
there is no benefit to the selection of tow/haul when the
vehicle is unloaded. Such a selection when unloaded
may result in unpleasant engine and transmission
driving characteristics and reduced fuel economy.
Tow/haul is recommended only when pulling a heavy
trailer or a large or heavy load.

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4-58 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.
Use one of the following charts to determine how much
your vehicle can weigh, based upon your vehicle model
and options.
Maximum trailer weight is calculated assuming the
driver and one passenger are in the tow vehicle and it
has all the required trailering equipment. The weight of
additional optional equipment, passengers and cargo in
the tow vehicle must be subtracted from the maximum
trailer weight.
Above the 5,000 lbs. (2 268 kg) trailer rating, the
handling/trailering suspension is required on C
-1500
models and the handling/trailering or off
-road
suspension is required on K
-1500 models. The engine
oil cooler is required on C/K
-2500 models with the
VORTEC 6000 engine. Refer to the Trailering Guide for
oil cooler recommendations.C
-1500 (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4300 V6 (Auto) 3.08 4,000 lbs. (1 814 kg)
3.42 4,500 lbs. (2 041 kg)
3.73 5,000 lbs. (2 268 kg)
4300 V6 (Manual) 3.08 3,500 lbs. (1 588 kg)
3.42 4,000 lbs. (1 814 kg)
4800 V8 (Auto) 3.42 6,000 lbs. (2 722 kg)
3.73 7,000 lbs. (3 175 kg)
4800 V8 (Manual) 3.42 4,000 lbs. (1 814 kg)
3.73 5,000 lbs. (2 268 kg)
5300 V8 3.42 7,000 lbs. (3 175 kg)
3.73 8,200 lbs. (3 720 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,000 lb. (454 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of hitch
pulling weight 1,500 lb (680 kg) maximum.

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4-59
K-1500 (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4300 V6 (Auto) 3.42 4,000 lbs. (1 814 kg)
3.73 4,500 lbs. (2 041 kg)
4300 V6 (Manual) 3.42 3,500 lbs. (1 588 kg)
3.73 4,000 lbs. (1 814 kg)
4800 V8 (Auto) 3.73 6,500 lbs. (2 948 kg)
4.10 7,500 lbs. (3 402 kg)
4800 V8 (Manual) 3.73 4,500 lbs. (2 041 kg)
4.10 5,500 lbs. (2 495 kg)
5300 V8 3.73 7,500 lbs. (3 402 kg)
4.10 8,000 lbs. (3 629 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,000 lb. (454 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of hitch
pulling weight 1,500 lb (680 kg) maximum.C
-2500 LD (2WD)*
Engine Axle
RatioMax. Trailer Wt.
5300 V8 3.42 6,500 lbs. (2 948 kg)
3.73 7,500 lbs. (3 402 kg)
4.10 8,500 lbs. (3 856 kg)
6000 V8 3.42 7,500 lbs. (3 402 kg)
3.73 8,500 lbs. (3 856 kg)
4.10 10,500 lbs. (4 763 kg)
6.5 L Diesel 3.42 7,500 lbs. (3 402 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of hitch
pulling weight 2,000 lb (907 kg) maximum.

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4-60
C-2500 HD (2WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 3.42 7,500 lbs. (3 402 kg)
3.73 8,500 lbs. (3 856 kg)
4.10 10,500 lbs. (4 763 kg)
6.5 L Diesel 3.42 11,000 lbs. (4 990 kg)
4.10 11,000 lbs. (4 990 kg)
* Weight
-distributing hitch tongue weight 10% to
15% of hitch weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of hitch
weight 2,500 lb (1 134 kg) maximum. K
-2500 HD (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,000 lbs. (3 629 kg)
4.10 10,000 lbs. (4 536 kg)
6.5 L Diesel 3.42 10,500 lbs. (4 763 kg)
4.10 10,500 lbs. (4 763 kg)
* Weight
-distributing hitch tongue weight 10% to
15% of hitch weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of hitch
weight 2,500 lb (1 134 kg) maximum.
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
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7

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4-65
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) (or the
manual 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, see ªEngine
Overheatingº in the Index.
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.
5. If you have a four
-wheel-drive vehicle, be sure
the transfer case is in a drive gear and not in
NEUTRAL (N).
6. Release the regular brakes.

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4-66
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 firmly 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 won't move, even
when you're on fairly level ground, use the steps
that follow.
Always put the shift lever fully in PARK (P) with
the parking brake firmly set.
If the transfer case on four-wheel drive vehicles is
in NEUTRAL (N), 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 (N).
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 fluid (don't
overfill), engine oil, axle lubricant, belt, cooling system
and brake system. Each of these is covered in this
manual, and the Index will help you find 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.

5-
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5-1
Section 5 Problems on the Road
Here you'll find what to do about some problems that can occur on the road.
5
-2 Hazard Warning Flashers
5
-2 Other Warning Devices
5
-3 Jump Starting
5
-8 Towing Your Vehicle
5
-9 Engine Overheating5
-12 Cooling System
5
-18 Engine Fan Noise
5
-18 If a Tire Goes Flat
5
-18 Changing a Flat Tire
5
-34 If You're Stuck: In Sand, Mud, Ice or Snow

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5-4
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren't touching
each other. If they are, it could cause a ground
connection you don't want. You wouldn't be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake firmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL (N). If you have a four
-wheel-drive
vehicle, be sure the transfer case is not in
NEUTRAL (N).
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off all lamps
that aren't needed as well as radios. This will avoid
sparks and help save both batteries. In addition, it
could save your radio!
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.
4. Open the hoods and locate the positive (+) and
negative (
-) terminal locations on the other vehicle.
Your vehicle has a remote positive (+) jump starting
terminal and a remote negative (
-) jump starting
terminal. The remote positive (+) terminal is located
behind a red plastic cover near the engine accessory
drive bracket. To uncover the remote positive (+)
terminal, open the red plastic cover.
On all V8 engines, the remote negative (
-) terminal
is located on the engine accessory drive bracket. This
is marked ªGNDº on V8 engines. On V6 engines,
the remote negative (
-) terminal is located on a tab
attached to the engine accessory drive bracket where
it is marked ªGNDº.
You should always use the remote positive (+) and the
remote negative (
-) terminals instead of the positive (+)
and negative (
-) terminals on your battery.

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5-5
CAUTION:
Using a match near a battery can cause battery
gas to explode. People have been hurt doing this,
and some have been blinded. Use a flashlight if
you need more light.
Be sure the battery has enough water. You don't
need to add water to the ACDelco
battery
installed in every new GM vehicle. But if a
battery has filler caps, be sure the right amount
of fluid is there. If it is low, add water to take
care of that first. If you don't, explosive gas could
be present.
Battery fluid contains acid that can burn you.
Don't get it on you. If you accidentally get it in
your eyes or on your skin, flush the place with
water and get medical help immediately.
5. Check that the jumper cables don't have loose or
missing insulation. If they do, you could get a shock.
The vehicles could be damaged too.
Before you connect the cables, here are some basic
things you should know. Positive (+) will go to
positive (+) or a remote positive terminal if the
vehicle has one. Negative (
-) will go to a metal
engine part or a remote negative terminal if the
vehicle has one. Don't connect positive (+) to
negative (
-) or you'll get a short that would damage
the battery and maybe other parts too.
On vehicles equipped with dual batteries, make all
battery connections to the remote positive (+) and
remote negative (
-) terminals.
CAUTION:
Fans or other moving engine parts can injure you
badly. Keep your hands away from moving parts
once the engine is running.

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5-7
V8 Engine V6 Engine
9. When connecting the cable, be sure it is not near
any engine parts that will move.
10. Now start the vehicle with the good battery and run
the engine for awhile.
11. Try to start the vehicle with the dead battery.
If it won't start after a few tries, it probably
needs service.
12. Remove the cables in reverse order to prevent
electrical shorting. Take care that they don't touch
each other or any other metal.
A. Heavy Metal Engine Part
B. Good Battery
C. Dead Battery