wheel GMC SIERRA 2001 Workshop Manual

4-39
Highway Hypnosis
Is there actually such a condition as ªhighway hypnosisº?
Or is it just plain falling asleep at the wheel? Call it
highway hypnosis, lack of awareness, or whatever.
There is something about an easy stretch of road with
the same scenery, along with the hum of the tires on the
road, the drone of the engine, and the rush of the wind
against the vehicle that can make you sleepy. Don't let it
happen to you! If it does, your vehicle can leave the
road in less than a second, and you could crash and
be injured.
What can you do about highway hypnosis?
First, be aware that it can happen.
Then here are some tips:

Make sure your vehicle is well ventilated, with a
comfortably cool interior.

Keep your eyes moving. Scan the road ahead
and to the sides. Check your mirrors and your
instruments frequently.

If you get sleepy, pull off the road into a rest, service
or parking area and take a nap, get some exercise, or
both. For safety, treat drowsiness on the highway as
an emergency.
Hill and Mountain Roads
Driving on steep hills or mountains is different from
driving in flat or rolling terrain.

4-42
What's the worst time for this? ªWet ice.º Very cold
snow or ice can be slick and hard to drive on. But wet
ice can be even more trouble because it may offer the
least traction of all. You can get wet ice when it's about
freezing (32F; 0C) and freezing rain begins to fall.
Try to avoid driving on wet ice until salt and sand crews
can get there.Whatever the condition
-- smooth ice, packed, blowing
or loose snow
-- drive with caution.
Accelerate gently. Try not to break the fragile traction.
'If you accelerate too fast, the drive wheels will spin and
polish the surface under the tires even more.
Your anti
-lock brakes improve your vehicle's stability
when you make a hard stop on a slippery road. Even
though you have an anti
-lock braking system, you'll
want to begin stopping sooner than you would on dry
pavement. See ªAnti
-Lockº in the Index.

Allow greater following distance on any
slippery road.

Watch for slippery spots. The road might be
fine until you hit a spot that's covered with ice.
On an otherwise clear road, ice patches may appear
in shaded areas where the sun can't reach: around
clumps of trees, behind buildings or under bridges.
Sometimes the surface of a curve or an overpass
may remain icy when the surrounding roads are
clear. If you see a patch of ice ahead of you,
brake before you are on it. Try not to brake
while you're actually on the ice, and avoid sudden
steering maneuvers.

4-45
Recreational Vehicle Towing
There may be times when you want to tow your vehicle
behind another vehicle for use at your destination.
Be sure to use the proper towing equipment designed
for recreational vehicle towing. Follow the instructions
for the towing equipment.
When towing your vehicle, turn the ignition to OFF. To
prevent your battery from draining while towing, remove
the IGN 0 fuse from the instrument panel fuse block.
Be sure to replace the fuse when you reach your destination.
See ªFuses and Circuit Breakersº in the Index.
Two-Wheel-Drive Vehicles
Tw o-wheel-drive vehicles, should not be towed
with all four wheels on the ground. Two
-wheel-drive
transmissions have no provisions for internal lubrication
while being towed. To properly tow these vehicles,
they should be placed on a platform trailer with all
four wheels off the ground.
In rare cases when it's unavoidable that a
two
-wheel-drive vehicle is to be towed with all four
wheels on the ground, the propeller shaft to axle yoke
orientation should be marked and the propeller shaft
removed following the applicable service manual
removal/installation procedure.
Dust or dirt can enter the back of the transmission
through the opening created by removing the propeller
shaft if proper protection is not provided. Also, check
the transmission fluid level before driving the truck.

4-46 Four-Wheel-Drive Vehicles
CAUTION:
Shifting the transfer case into NEUTRAL can
cause your vehicle to roll even if the transmission
is in PARK (P), for an automatic transmission,
or if your vehicle is in gear, for a manual
transmission. You or others could be injured.
Make sure the parking brake is firmly set before
you shift the transfer case into NEUTRAL.
Use the following procedure to correctly tow your
vehicle on all four wheels:
1. Firmly set the parking brake.
2. Shift an automatic transmission to PARK (P),
or a manual transmission to FIRST (1).
3. Securely attach the vehicle being towed to the
tow vehicle.
4. Shift the transfer case to NEUTRAL (N).
See ªFour
-Wheel Driveº in the Index for the
proper procedure to select the neutral position for
your vehicle.
5. Release the parking brake only after the vehicle
being towed is firmly attached to the towing vehicle.
6. Turn the ignition to OFF. The OFF position unlocks
the steering column and reduces battery drain as long
as the IGN 0 fuse is removed. Unlocking the steering
column will allow the proper movement of the front
wheels and tires during towing.

4-51
Q:What is front axle reserve capacity, and how
do I calculate it?
A:Front axle reserve capacity is the difference
between your front GAWR and the front axle
weight of your truck with full fuel and passengers.
Basically, it's the amount of weight you can add to
your front axle before reaching your front GAWR.
The front axle reserve
capacity for your
vehicle can be
found in the lower
right corner of the
tire/certification label.In order to calculate the amount of weight any front
accessory, such as a snow plow, is adding to the
front axle, use the following formula:
(W x (A + W.B))/W.B.= Weight the accessory is
adding to the front axle.
Where:
W=Weight of added accessory
A=Distance that the accessory is in front of the
A=front axle
W.B.=Vehicle Wheelbase

4-52
For example, adding a 700 lb. (318 kg) snow plow
actually adds more than 700 lb. (318 kg) to the
front axle. Using the formula, if the snow plow is
4 ft. (122 cm) in front of the front axle and the
wheel base is 10 ft. (305 cm), then:
W=700 lb. (318 kg)
A=4 ft. (122 cm)
W.B.=10 ft. (305 cm)
(W x (A + W.B.))/W.B.= (700 x (4 + 10))/10 =
980 lb. (445 kg)
So, if your truck's front axle reserve capacity is
more than 980 lb. (445 kg), you could add this
snow plow without exceeding the front GAWR.
Q:What if I want to add heavier equipment to
my vehicle?
A:You can add heavier equipment on the front of the
vehicle if you compensate for it by carrying fewer
passengers, less cargo, or by positioning cargo more
towards the rear. This has the effect of reducing the
load on the front. However, the front GAWR, rear
GAWR and the GVWR must never be exceeded.
CAUTION:
On some vehicles equipped with certain front
mounted equipment, such as a snow plow, it may
be possible to load the front axle to the front
GAWR but not have enough weight on the rear
axle to have proper braking performance.
If your brakes can't work properly, you could
have a crash. To help your brakes work properly
when a snow plow is installed, always follow
the snow plow manufacturer or installer's
recommendation for rear ballast to ensure a
proper front and rear weight distribution ratio,
even though the actual front weight may be less
than the front GAWR, and the total vehicle
weight is less than the GVWR. Maintaining a
proper front and rear weight distribution ratio is
necessary to provide proper braking performance.

4-55
Your dealer can help you make a good vehicle-camper
match. He'll also help you determine your CWR.
After you've loaded your vehicle and camper, drive to
a weigh station and weigh the front and rear wheels
separately. This will tell you the loads on your axles.
The loads on the front and rear axles shouldn't be more
than either of the GAWRs. The total of the axle loads
should not be more than the GVWR.
Open your driver's door and look at the
Certification/Tire label to find out your GAWR
and GVWR.
If you've gone over your weight ratings, move or
take out some things until all the weight falls below
the ratings. Of course, you should always tie down
any loose items when you load your vehicle or camper.
When you install and load your slide
-in camper,
check the manufacturer's instructions.
If you want more information on curb weights, cargo
weights, Cargo Weight Rating and the correct center of
gravity zone for your vehicle, your dealer can help you.
Just ask for a copy of ªConsumer Information,
Truck
-Camper Loading.º
Trailer Recommendations
You must subtract your hitch loads from the CWR
for your vehicle. Weigh your vehicle with the trailer
attached, so that you won't go over the GVWR or
GAWR. If you are using a weight
-distributing hitch,
weigh the vehicle without the equalizer bars in place.
You'll get the best performance if you spread out the
weight of your load the right way, and if you choose the
correct hitch and trailer brakes.
For more information, see ªTrailer Towingº in
the Index.
Camper Wiring Harness
(If Equipped)
If your vehicle is equipped with a camper wiring
harness, see ªTrailer Wiring Harnessº in the Index
for further information.

4-60
C-1500 Regular Cab Short Box (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4300 V6 (Auto) 3.08 4,700 lbs. (2 132 kg)
3.42 5,200 lbs. (2 359 kg)
4300 V6 (Manual) 3.08 3,700 lbs. (1 678 kg)
3.42 4,200 lbs. (1 905 kg)
4800 V8 (Auto) 3.42 6,600 lbs. (2 994 kg)
3.73 7,600 lbs. (3 447 kg)
4800 V8 (Manual) 3.42 4,600 lbs. (2 087 kg)
3.73 5,600 lbs. (2 540 kg)
5300 V8 3.42 7,600 lbs. (3 447 kg)
3.73 8,600 lbs. (3 901 kg)C-1500 Extended Cab Short Box (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4300 V6 (Auto) 3.42 4,900 lbs. (2 223 kg)
3.73 5,900 lbs. (2 676 kg)
4300 V6 (Manual) 3.42 3,900 lbs. (1 769 kg)
4800 V8 (Auto) 3.42 6,300 lbs. (2 858 kg)
3.73 7,300 lbs. (3 311 kg)
4800 V8 (Manual) 3.42 4,300 lbs. (1 950 kg)
3.73 5,300 lbs. (2 404 kg)
5300 V8 3.42 7,300 lbs. (3 311 kg)
3.73 8,300 lbs. (3 765 kg)
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,000 lb. (454 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 1,500 lb. (680 kg) maximum.

4-61
C-1500 Crew Cab Short Box (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,300 lbs. (3 765 kg)
4.10 10,300 lbs. (4 672 kg)
C
-1500 Regular Cab Long Box (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4300 V6 (Auto) 3.08 4,600 lbs. (2 087 kg)
3.42 5,100 lbs. (2 313 kg)
4300 V6 (Manual) 3.08 3,600 lbs. (1 633 kg)
3.42 4,100 lbs. (1 860 kg)
4800 V8 (Auto) 3.42 6,500 lbs. (2 948 kg)
3.73 7,500 lbs. (3 402 kg)
4800 V8 (Manual) 3.42 4,500 lbs. (2 041 kg)
3.73 5,500 lbs. (2 495 kg)
5300 V8 3.42 7,500 lbs. (3 402 kg)
3.73 8,500 lbs. (3 856 kg)C
-1500 Extended Cab Long Box (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4800 V8 (Auto) 3.42 6,100 lbs. (2 767 kg)
3.73 7,100 lbs. (3 220 kg)
4800 V8 (Manual) 3.42 4,100 lbs. (1 860 kg)
3.73 5,100 lbs. (2 313 kg)
5300 V8 3.42 7,100 lbs. (3 220 kg)
3.73 8,100 lbs. (3 674 kg)
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,000 lb. (454 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 1,500 lb. (680 kg) maximum.

4-62
K-1500 Regular Cab Short Box (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4300 V6 (Auto) 3.42 4,900 lbs. (2 223 kg)
3.73 5,400 lbs. (2 449 kg)
4300 V6 (Manual) 3.42 3,900 lbs. (1 769 kg)
3.73 4,400 lbs. (1 996 kg)
4800 V8 (Auto) 3.73 7,300 lbs. (3 311 kg)
4.10 8,300 lbs. (3 765 kg)
4800 V8 (Manual) 3.73 5,300 lbs. (2 404 kg)
4.10 6,300 lbs. (2 858 kg)
5300 V8 3.73 8,300 lbs. (3 765 kg)
4.10 9,300 lbs. (4 218 kg)K-1500 Extended Cab Short Box (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4800 V8 (Auto) 3.73 7,000 lbs. (3 175 kg)
4.10 8,000 lbs. (3 629 kg)
4800 V8 (Manual) 3.73 5,000 lbs. (2 268 kg)
4.10 6,000 lbs. (2 624 kg)
5300 V8 3.73 8,000 lbs. (3 629 kg)
4.10 9,000 lbs. (4 082 kg)
K
-1500 Crew Cab Short Box (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,000 lbs. (3 629 kg)
4.10 10,000 lbs. (4 536 kg)
* Weight
-distributing hitch tongue weight 10% to 15% of trailer weight 1,000 lb. (454 kg) maximum.
Fifth
-wheel hitch tongue weight 15% to 25% of trailer weight 1,500 lb. (680 kg) maximum.