engine GMC SIERRA 2001 Manual Online

4-67
K-2500 Regular Cab Long Box HD (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 10,400 lbs. (4 717 kg)
8100 V8 3.73 13,700 lbs. (6 214 kg)**
4.10 15,700 lbs. (7 121 kg)**
6600 V8 Diesel 3.73 15,600 lbs. (7 076 kg)**
4.10 15,600 lbs. (7 076 kg)**K-2500 Extended Cab Long Box HD (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 10,200 lbs. (4 627 kg)
8100 V8 3.73 13,500 lbs. (6 123 kg)**
4.10 15,500 lbs. (7 031 kg)**
6600 V8 Diesel 3.73 15,500 lbs. (7 031 kg)**
4.10 15,500 lbs. (7 031 kg)**
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 2,500 lb. (1 134 kg) maximum.
** Fifth
-wheel hitch rating; weight distributing hitch rating is limited to 12,000 lbs. (5 443 kg) maximum.

4-68
K-2500 Crew Cab Short Box HD (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 10,000 lbs. (4 536 kg)
8100 V8 3.73 13,200 lbs. (5 987 kg)**
4.10 15,200 lbs. (6 895 kg)**
6600 V8 Diesel 3.73 15,200 lbs. (6 895 kg)**
4.10 15,200 lbs. (6 895 kg)**K-2500 Crew Cab Long Box HD (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 9,900 lbs. (4 491 kg)
8100 V8 3.73 13,200 lbs. (5 987 kg)**
4.10 15,200 lbs. (6 895 kg)**
6600 V8 Diesel 3.73 15,100 lbs. (6 849 kg)**
4.10 15,100 lbs. (6 849 kg)**
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 2,500 lb. (1 134 kg) maximum.
** Fifth
-wheel hitch rating; weight distributing hitch rating is limited to 12,000 lbs. (5 443 kg) maximum.

4-69
C-3500 Regular Cab HD (2WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 10,400 lbs. (4 717 kg)
8100 V8 4.10 15,700 lbs. (7 121 kg)**
6600 V8 Diesel 3.73 15,800 lbs. (7 167 kg)**
4.10 15,800 lbs. (7 167 kg)**
C
-3500 Extended Cab (2WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 10,100 lbs. (4 581 kg)
8100 V8 4.10 15,400 lbs. (6 985 kg)**
6600 V8 Diesel 3.73 15,500 lbs. (7 031 kg)**C
-3500 Crew Cab (2WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 9,900 lbs. (4 491 kg)
8100 V8 4.10 15,300 lbs. (6 940 kg)**
6600 V8 Diesel 3.73 15,400 lbs. (6 985 kg)**
4.10 15,400 lbs. (6 985 kg)**
K
-3500 Regular Cab (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 10,100 lbs. (4 582 kg)
8100 V8 4.10 15,500 lbs. (7 031 kg)**
6600 V8 Diesel 3.73 15,400 lbs. (6 985 kg)**
4.10 15,400 lbs. (6 985 kg)**
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 2,500 lb. (1 134 kg) maximum.
** Fifth
-wheel hitch rating; weight distributing hitch rating is limited to 12,000 lbs. (5 443 kg) maximum.

4-70
K-3500 Extended Cab (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 9,800 lbs. (4 445 kg)
8100 V8 4.10 15,100 lbs. (6 849 kg)**
6600 V8 Diesel 3.73 14,800 lbs. (6 713 kg)**
4.10 14,800 lbs. (6 713 kg)**K-3500 Crew Cab (4WD)*
Engine Axle
RatioMax. Trailer Wt.
6000 V8 4.10 9,800 lbs. (4 445 kg)
8100 V8 4.10 15,100 lbs. (6 849 kg)**
6600 V8 Diesel 3.73 15,200 lbs. (6 895 kg)**
4.10 15,200 lbs. (6 895 kg)**
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,200 lb. (544 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 2,500 lb. (1 134 kg) maximum.
** Fifth
-wheel hitch rating; weight distributing hitch rating is limited to 12,000 lbs. (5 443 kg) maximum.

4-75 Turn Signals When Towing a Trailer
The arrows on your instrument panel will flash
whenever you signal a turn or lane change. Properly
hooked up, the trailer lamps will also flash, telling other
drivers you're about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will flash 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 gear before you 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 THIRD (3) or, if necessary, 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. See ªTow/Haul Modeº in
the Index.
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) (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.

4-76 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.
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, 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.

4-77 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.
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 Package
All regular, extended cab crew cab pickups have a
six
-wire trailer towing harness.
The six-wire harness is located at the rear of the vehicle
and is tied to the vehicle's frame. The harness requires
the installation of a trailer
-wiring harness connector,
which is available through your dealer.

4-82 Power Take-Off (PTO) (If Equipped)
NOTICE:
If you have a PTO that will exceed 35 hp installed on
your vehicle, it could damage the transfer case or
transmission. When having a PTO installed on your
vehicle, make sure that it will not exceed 35 hp.
Before using a PTO, refer to the manufacturer's or
installer's instructions.
NOTICE:
Using a PTO while operating in one place before
the vehicle has reached normal operating
temperature can damage the transfer case or
transmission. If you will be using the PTO while
operating in one place, drive and warm up the
vehicle before using the PTO.
To engage a PTO on a vehicle with a
manual transmission:
1. Hold the clutch pedal down.
2. Set the parking brake.
3. Shift the transmission into NEUTRAL (N).
4. Engage the PTO. Refer to the manufacturer's
or installer's for instructions on electrically
engaged PTOs.
5. For mobile operations, shift the transmission into
the gear you want, apply the regular brakes and
release the parking brake. For stationary operations,
leave the parking brake applied.
6. Release the clutch and regular brakes as you
normally would. When the clutch is released,
the PTO will start.
7. Turn the PTO rotary switch to ON.
To engage a PTO on a vehicle with an
automatic transmission:
1. Engine speed must be less than 1000 rpm.
2. Turn the PTO rotary switch ON.

4-83
Using PTO speed control in Preset Mode
(Factory Setting):
1. Engage the PTO.
2. Select PARK (P) or NEUTRAL (N) range.
Apply the parking brake in NEUTRAL (N) is
selected. Torque Converter Clutch (TCC) lockup is
not available in NEUTRAL (N) and is available only
in PARK when engine speed is above 1100 rpm.
3. Make sure your foot is off the brake pedal
(and off the clutch on vehicles equipped with a
manual transmission). Select the desired engine
speed for PTO operation. Please read the following
Preset Mode information regarding operation.
Preset Mode: PTO speed control mode is used for
stationary applications. This mode provides a default
standby speed of 800 or 850 rpm (depending on the
engine/transmission combination) and two default PTO
control speeds which follow:

PTO Fast Idle Speed of 1250 rpm, or

PTO Fast Idle Resume Speed of 1700 rpm.
Standby speed (800/850 rpm) is not to be used as a
PTO control speed. Vehicles not equipped with cruise
control will not have the resume speed capability.Using PTO speed control in Variable Mode (Mobile):
1. Engage the PTO.
2. Vehicle speed must be greater than 5 mph for vehicles
equipped with gasoline engines or greater than 0 mph
for vehicles equipped with diesel engines.
3. Make sure your foot is off the brake pedal
(and off the clutch for vehicles equipped with a
manual transmission).
4. Select the desired engine speed (with the foot pedal)
and select SET on the PTO switch or with the
cruise control.
Using PTO speed control in Variable
Mode (Stationary):
1. Engage the PTO.
2. Vehicle speed must be less than 5 mph for vehicles
equipped with gasoline engines or at 0 mph for
vehicles equipped with diesel engines.
3. Make sure your foot is off the brake pedal
(and off the clutch for vehicles equipped with a
manual transmission).
4. Select the desired engine speed (with the foot pedal)
and select SET on the PTO switch or with the
cruise control.

4-84
Variable Mode: PTO speed control mode can be used
for both stationary and mobile applications. This mode
allows PTO to be controlled in a fashion similar to how
cruise control sets vehicle speed. The operator can set to
an rpm (between 800 and 2200) with the cruise control
feature or with the SET position on the PTO switch.
The operator is then able to increase engine speed in
100 rpm increments with the resume position on the
cruise control. The operator can also decrease engine
speed in 100 rpm increments with either the SET
position on the cruise control or the PTO switch.
Vehicles not equipped with cruise control will not
have the resume capability.
All engine speed values listed above are factory preset
values. With the exception of the TCC lockup speed
(1100 rpm) and the ªtapº increment (100 rpm), all of
these values are programmable and can be adjusted by
your GM dealer or body upfitter. If the PTO software
settings do not match the settings shown here, then
they may have already been altered in order to satisfy
the requirements of the installed PTO system and
body equipment.Step-Bumper Pad
If your vehicle has a rear step bumper, it may be
equipped with a rear step pad at the center of
the bumper.
If you will be using the
bumper to tow a trailer,
you must remove the
center cutout circle to
install the trailer ball.