1999 GMC SUBURBAN Owner's Manual

4-54
C-1500 (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4800 V8 3.42 6,100 lbs. (2 767 kg)
3.73 7,100 lbs. (3 221 kg)
5300 V8 3.42 7,100 lbs. (3 221 kg)
3.73 8,100 lbs. (3 674 kg)
5300 V8 3.73 8,000 lbs. (3 629 kg)
(Suburban/
Yukon XL)4.10 9,000 lbs. (4 082 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.K
-1500 (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
4800 V8 3.73 6,800 lbs. (3 084 kg)
4.10 7,800 lbs. (3 538 kg)
5300 V8 3.73 7,800 lbs. (3 538 kg)
4.10 8,800 lbs. (3 992 kg)
5300 V8 3.73 7,800 lbs. (3 538 kg)
(Suburban/
Yukon XL)4.10 8,800 lbs. (3 992 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.

4-55
C-2500 LD (2WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,500 lbs. (3 856 kg)
(Suburban/
Yukon XL)4.10 10,500 lbs. (4 763 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 kg) maximum.K
-2500 HD (4WD)*
Engine (Trans.) Axle
RatioMax. Trailer Wt.
6000 V8 3.73 8,100 lbs. (3 674 kg)
(Suburban/
Yukon XL)4.10 10,100 lbs. (4 581 kg)
* Weight
-distributing hitch tongue weight 10% to 15%
of hitch pulling weight 1,200 lbs. (544 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

4-56 Weight of the Trailer Tongue
The tongue load (A) of any trailer is an important
weight to measure because it affects the total or gross
weight of your vehicle. The Gross Vehicle Weight
(GVW) includes the curb weight of the vehicle, any
cargo you may carry in it, and the people who will be
riding in the vehicle. And if you will tow a trailer, you
must add the tongue load to the GVW because your
vehicle will be carrying that weight, too. See ªLoading
Your Vehicleº in the Index for more information about
your vehicle's maximum load capacity.
If you're using a weight-carrying or a weight-distributing
hitch, the trailer tongue weight (A) should be 10 percent
to 15 percent of the total loaded trailer weight (B).
Do not exceed the maximum allowable tongue weight
for your vehicle.
After you've loaded your trailer, weigh the trailer and
then the tongue, separately, to see if the weights are
proper. If they aren't, you may be able to get them
right simply by moving some items around in the trailer.
Total Weight on Your Vehicle's Tires
Be sure your vehicle's tires are inflated to the upper
limit for cold tires. You'll find these numbers on the
Certification label at the rear edge of the driver's door or
see ªTire Loadingº in the Index. Then be sure you
don't go over the GVW limit for your vehicle, including
the weight of the trailer tongue.

4-57 Hitches
It's important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads
are a few reasons why you'll need the right hitch.
Here are some rules to follow:

If you use a step
-bumper hitch, your bumper could
be damaged in sharp turns. Make sure you have
ample room when turning to avoid contact between
the trailer and the bumper.

If you'll be pulling a trailer that, when loaded, will
weigh more than the capacity stamped on your
step bumper, 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
you're driving.
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.
For trailers up to 5,000 lbs. (2 270 kg) you may
attach the safety chains to the attaching points on the
bumper. For heavier trailers, follow the trailer or hitch
manufacturer's recommendation for attaching safety
chains. If you have the factory
-installed trailering
package, for vehicles equipped to pull a trailer up to
10,500 lbs. (4 763 kg), you may attach the safety chains
to the attaching point on the hitch platform. Always
leave just enough slack so you can turn with your rig.
Never allow safety chains to drag on the ground.

4-58 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 inches (0.3 cc) of fluid 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 fluid
to the rear brakes. But don't use copper tubing for this.
If you do, it will bend and finally break off. Use steel
brake tubing.
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 can't see or
smell CO. It can cause unconsciousness or death.
(See ªEngine Exhaustº in the Index.) 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 MAX A/C because it
only recirculates the air inside your vehicle.
(See ªComfort Controlsº in the Index.)

4-59
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 the trailer hitch and platform
(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.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.
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.

4-60 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 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.
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.
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. If you do get
the overheat warning, see ªEngine Overheatingº in
the Index.

4-61 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 brake, but don't shift into
PARK (P) yet.
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).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 (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).