2000 GMC YUKON Front axle

2-22 Tow/Haul Mode Selector Switch
Your vehicle is equipped with a tow/haul mode. The
selector switch is located on the end of the column shift
lever. You can use this feature to assist when towing or
hauling a heavy load. See ªTow/Haul Modeº in the
Index for more information.
The Tow/Haul Mode also interacts with the Autoride

feature, if your vehicle is so equipped, to enhance the ride
when trailering or with a loaded vehicle. See ªAutoride
º
in the Index.
Four-Wheel Drive (If Equipped)
If your vehicle has four-wheel drive, you can send your
engine's driving power to all four wheels for extra
traction. To get the most satisfaction out of four
-wheel
drive, you must be familiar with its operation. Read the
part that follows before using four
-wheel drive. See the
appropriate text for the transfer case in your vehicle.
NOTICE:
Driving in the 4-WHEEL HIGH (4H) or
4
-WHEEL LOW (4L) positions for a long time
on dry or wet pavement could shorten the life
of your vehicle's drivetrain.
Front Axle Locking Feature
The front axle locks and unlocks automatically when
you shift the transfer case. Some delay for the axle to
lock or unlock is normal.

2-23 Automatic Transfer Case (If Equipped)
The transfer case switches
are located to the left of the
instrument panel cluster.
Use these switches to shift into and out of
four
-wheel drive.
You can choose among four driving settings:
2HI: This setting is used for driving in most street and
highway situations. Your front axle is not engaged in
two
-wheel drive. This setting also provides the best
fuel economy.

2-24
AUTO 4WD: This setting is ideal for use when road
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle's
power is sent only to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four
-wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.
4HI: Use 4HI when you need extra traction, such as
on snowy or icy roads or in most off
-road situations.
This setting also engages your front axle to help drive
your vehicle. This is the best setting to use when
plowing snow.
4LO: This setting also engages your front axle and
delivers extra torque. You may never need 4LO. It sends
maximum power to all four wheels. You might choose
4LO if you are driving off
-road in deep sand, deep mud,
deep snow and climbing or descending steep hills.
CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the transmission
is in PARK (P). You or someone else could be
seriously injured. Be sure to set the parking
brake before placing the transfer case in
NEUTRAL. See ªParking Brakeº in the Index.
NEUTRAL: Shift the vehicle's transfer case to NEUTRAL
only when towing your vehicle. See ªRecreational Vehicle
Towingº or ªTowing Your Vehicleº in the Index for
more information.
Indicator lights in the switches show which setting you are
in. The indicator lights will come on briefly when you turn
on the ignition and one will stay on. If the lights do not
come on, you should take your vehicle to your dealer for
service. An indicator light will flash while shifting the
transfer case. It will remain illuminated when the shift is
complete. If for some reason the transfer case cannot make
a requested shift, it will return to the last chosen setting.

4-46
Loading Your Vehicle
The Certification/Tire label is found on the rear edge of
the driver's door or in the Incomplete Vehicle Document
in the cab.The label shows the size of your original tires and the
inflation pressures needed to obtain the gross weight
capacity of your vehicle. This is called the GVWR
(Gross Vehicle Weight Rating). The GVWR includes
the weight of the vehicle, all occupants, fuel and cargo.
The Certification/Tire label also tells you the maximum
weights for the front and rear axles, called Gross Axle
Weight Rating (GAWR). To find out the actual loads
on your front and rear axles, you need to go to a weigh
station and weigh your vehicle. Your dealer can help
you with this. Be sure to spread out your load equally
on both sides of the centerline.
Never exceed the GVWR for your vehicle, or the
GAWR for either the front or rear axle.
The Certification/Tire label also contains information
about your Front Axle Reserve Capacity. See ªFront
Axle Reserve Capacityº later in this section.
And, if you do have a heavy load, you should spread
it out.

4-47
NOTICE:
Some vehicles may be equipped with RPO VYU
(snow plow prep package). With this option, the
payload your vehicle can carry is reduced when
a snow plow is installed. Your vehicle can be
damaged if either the front or rear axle ratings,
or the GVW are exceeded.
As a general guideline, with a 650 lb. (295 kg)
snow plow, the weight of the occupants and cargo
must not exceed 300 lb. (135 kg). However, this
may depend on the vehicle's option content.
Therefore, to help avoid vehicle damage:

Make sure the weight on the front and
rear axles does not exceed their respective
axle ratings.
NOTICE: (Continued)
NOTICE: (Continued)

For the front axle, if more cargo or
passengers need to be carried, appropriate
counter ballast must be installed rear of
the rear axle and properly secured.

Total vehicle weight must not exceed the
GVW rating.

See your dealer for advice and information
about using a snow plow on your vehicle.
CAUTION:
Do not load your vehicle any heavier than the
GVWR, or either the maximum front or rear
GAWR. If you do, parts on your vehicle can
break, and it can change the way your vehicle
handles. These could cause you to lose control
and crash. Also, overloading can shorten the life
of your vehicle.

4-49 Front Axle Reserve Capacity
This is the difference between your front GAWR and
the front axle weight of your truck with full fuel and
passengers. It is 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 hand corner of the
tire/certification label, as
shown in this example.
In order to calculate the amount of weight any
front accessory 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 front axle
W.B.= Vehicle Wheelbase

4-50
For example, adding a 700 lb. ( 318 kg) snow plow
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) and
W.B.= 10 ft. (305 cm)
(W x (A+W.B.)) / W.B. = (700 x (4ft. + 10 ft.)) /
10 ft. = 980 lbs.
So, if your truck's front axle reserve capacity is more
than 980 lbs. (445 kg), you could add this snow plow
without exceeding the front GAWR.
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.Total Vehicle Reserve Capacity
This is the difference between your GVWR and the
weight of your truck with full fuel and passengers.
It is the amount of weight you can add to your vehicle
before reaching your GVWR.
The reserve capacity numbers are intended as a guide
when selecting the amount of equipment or cargo your
truck can carry. If you are unsure of your truck's front,
rear or total weight, go to a weigh station and weigh
your vehicle. Your dealer can help you with this.
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.

5-24
Position the jack under the vehicle. If the flat tire
is on the front of the vehicle, position the jack on
the frame behind the flat tire where the frame
sections overlap.
On all 1500 Series vehicles, use the jacking pad
provided on the rear axle. On 2500 Series vehicles,
use the axle between the spring and shock.
If you have added a snow plow to the front of
your vehicle, lower the snow plow fully before
raising the vehicle.
CAUTION:
Getting under a vehicle when it is jacked up is
dangerous. If the vehicle slips off the jack, you
could be badly injured or killed. Never get under
a vehicle when it is supported only by a jack.
CAUTION:
Raising your vehicle with the jack improperly
positioned can damage the vehicle and even
make the vehicle fall. To help avoid personal
injury and vehicle damage, be sure to fit the jack
lift head into the proper location before raising
the vehicle.