2010 BUICK ENCLAVE Owner's Manual

Driving and Operating 9-47
Tow/Haul Mode
Tow/Haul 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.
.Provide the same solid shift feel
as when the vehicle is unloaded.
.Improve control of vehicle speed
while requiring less throttle pedal
activity.
.Increase the charging system
voltage to assist in recharging a
battery installed in a trailer.
Press this button located on the
console to turn on and turn off the
Tow/Haul mode.
The Tow/Haul light on the
instrument panel comes on to
indicate that Tow/Haul mode 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 percent of the vehicle's Gross
Combined Weight Rating (GCWR).
See
Trailer Towing
on page 9‑50.
Tow/Haul is most useful when
pulling a heavy trailer or a large or
heavy load under the following
driving conditions:
.Travelling through rolling terrain.
.Travelling in stop and go traffic.
.Travelling 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
will not cause damage but there is
no benefit. Such a selection when
unloaded may result in unpleasant
engine and transmission driving
characteristics and reduced fuel
economy.

9-48 Driving and Operating
Following Distance
Stay at least twice as far behind the
vehicle ahead as you would when
driving the vehicle without a trailer.
This can help to avoid situations
that require heavy braking and
sudden turns.
Passing
More passing distance is needed
when towing a trailer. Because the
rig is longer, it is necessary to go
farther beyond the passed vehicle
before returning to the lane.
Backing Up
Hold the bottom of the steering
wheel with one hand. To move the
trailer to the left, 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.
Making Turns
Notice:Making very sharp turns
while trailering could cause the
trailer to come in contact with the
vehicle. The vehicle could be
damaged. Avoid making very
sharp turns while trailering.
When turning with a trailer, make
wider turns than normal so the
trailer will not strike soft shoulders,
curbs, road signs, trees or other
objects. Use the turn signal well in
advance and avoid jerky or sudden
maneuvers.
Turn Signals When Towing a
Trailer
The turn signal indicators on the
instrument panel flash whenever
signaling a turn or lane change.
Properly hooked up, the trailer
lamps also flash, telling other
drivers the vehicle is turning,
changing lanes or stopping. When towing a trailer, the arrows on
the instrument panel flash for turns
even if the bulbs on the trailer are
burned out. Check occasionally to
be sure the trailer bulbs are still
working.
Driving On Grades
Reduce speed and shift to a
lower gear before starting down a
long or steep downgrade. If the
transmission is not shifted down, the
brakes might have to be used so
much that they would get hot and no
longer work well.
The vehicle can tow in D (Drive).
Use a lower gear if the transmission
shifts too often.

Driving and Operating 9-49
When towing at high altitude on
steep uphill grades, engine coolant
will boil at a lower temperature than
at normal altitudes. If the engine is
turned off immediately after towing
at high altitude on steep uphill
grades, the vehicle may show signs
similar to engine overheating. To
avoid this, let the engine run while
parked, preferably on level ground,
with the transmission in P (Park) for
a few minutes before turning the
engine off. If the overheat warning
comes on, seeEngine Overheating
on page 10‑18.
On a long uphill grade, shift down
and reduce the vehicle speed to
around 88 km/h (55 mph) to reduce
the possibility of the engine and the
transmission overheating.
Parking on Hills
{WARNING
Parking the vehicle on a hill with
the trailer attached can be
dangerous. If something goes
wrong, the rig could start to move.
People can be injured, and both
the vehicle and the trailer can be
damaged. When possible, always
park the rig on a flat surface.
If parking the rig on a hill:
1. Press the brake pedal, but do not shift into P (Park) yet. Turn
the wheels into the curb if facing
downhill or into traffic if facing
uphill.
2. Have someone place chocks under the trailer wheels. 3. When the wheel chocks are in
place, release the brake pedal
until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift
into P (Park).
5. Release the brake pedal.
Leaving After Parking on a Hill
1. Apply and hold the brake pedal while you:
.Start the engine.
.Shift into a gear.
.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.

9-50 Driving and Operating
Maintenance When Trailer
Towing
The vehicle needs service more
often when pulling a trailer. See this
manual's Maintenance Schedule or
Index for more information. Things
that are especially important in
trailer operation are automatic
transmission fluid, engine oil, axle
lubricant, belts, cooling system and
brake system. Inspect these before
and during the trip.
Check periodically to see that all
hitch nuts and bolts are tight.
Engine Cooling When Trailer
Towing
The cooling system may temporarily
overheat during severe operating
conditions. SeeEngine Overheating
on page 10‑18.
Trailer Towing
Three important considerations
have to do with weight:
.The weight of the trailer
.The weight of the trailer tongue
.The total weight on the vehicle's
tires
Weight of the Trailer
How heavy can a trailer safely be?
Speed, altitude, road grades,
outside temperature, special
equipment, and the amount of
tongue weight the vehicle can carry
must be considered. See “Weight of
the Trailer Tongue” later in this
section for more information.
Maximum trailer weight is calculated
assuming only the driver is 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.

Driving and Operating 9-51
Use the following chart to determine how much the vehicle can weigh, based upon the vehicle model and options.Vehicle Maximum Trailer Weight *GCWR
Front-Wheel Drive 2,000 lbs (907 kg) 7,500 lbs (3 402 kg)
Front-Wheel Drive, V92 Trailer Towing Package 4,500 lbs (2 041 kg) 9,500 lbs (4 309 kg)
All-Wheel Drive 2,000 lbs (907 kg) 7,700 lbs (3 493 kg)
All-Wheel Drive, V92 Trailer Towing Package 4,500 lbs (2 041 kg) 9,700 lbs (4 400 kg)
*The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and
trailer including any passengers, cargo, equipment and conversions. The GCWR for the vehicle should not be
exceeded.
Ask your dealer/retailer for our
trailering information or advice. See
Customer Assistance Offices (US,
Can)
on page 13‑3for more
information.
Weight of the Trailer Tongue
The tongue load (A) of any trailer is
an important weight to measure
because it affects the total gross
weight of the vehicle. The Gross
Vehicle Weight (GVW) includes the
curb weight of the vehicle, any
cargo carried in it, and the people
who will be riding in the vehicle.
If there are a lot of options, equipment, passengers or cargo in
the vehicle, it will reduce the tongue
weight the vehicle can carry, which
will also reduce the trailer weight the
vehicle can tow. If towing a trailer,
the tongue load must be added to
the GVW because the vehicle will
be carrying that weight, too. See
Vehicle Load Limits on page 9‑12

9-52 Driving and Operating
If a weight-carrying hitch or a
weight-distributing hitch is being
used, the trailer tongue (A) should
weigh 10-15 percent of the total
loaded trailer weight (B).
After loading the trailer, weigh the
trailer and then the tongue,
separately, to see if the weights are
proper. If they are not, adjustments
might be made by moving some
items around in the trailer.
Trailering may be limited by the
vehicle's ability to carry tongue
weight. Tongue weight cannot cause
the vehicle to exceed the GVWR(Gross Vehicle Weight Rating) or
the RGAWR (Rear Gross Axle
Weight Rating). The effect of
additional weight may reduce the
trailering capacity more than the
total of the additional weight.
Consider the following example:
A vehicle model base weight is
2 495 kg (5,500 lbs); 1 270 kg
(2,800 lbs) at the front axle and
1 225 kg (2,700 lbs) at the rear axle.
It has a GVWR of 3 266 kg
(7,200 lbs), a RGAWR of 1 814 kg
(4,000 lbs) and a GCWR (Gross
Combination Weight Rating) of
6 350 kg (14,000 lbs). The trailer
rating should be:
Expect tongue weight to be at least
10 percent of trailer weight (386 kg
(850 lbs)) and because the weight isapplied well behind the rear axle,
the effect on the rear axle is greater
than just the weight itself, as much
as 1.5 times as much. The weight at
the rear axle could be 386 kg
(850 lbs) X 1.5 = 578 kg (1,275 lbs).
Since the rear axle already weighs
1 225 kg (2,700 lbs), adding 578 kg
(1,275 lbs) brings the total to
1 803 kg (3,975 lbs). This is very
close to, but within the limit for
RGAWR as well. The vehicle is set
to trailer up to 3 856 kg (8,500 lbs).
If the vehicle has many options and
there is a front seat passenger and
two rear seat passengers with some
luggage and gear in the vehicle as
well. 136 kg (300 lbs) could be
added to the front axle weight and
181 kg (400 lbs) to the rear axle
weight. The vehicle now weighs:

Driving and Operating 9-53
Weight is still below 3 266 kg
(7,200 lbs) and you might think
318 additional kilograms (700 lbs)
should be subtracted from the
trailering capacity to stay within
GCWR limits. The maximum trailer
would only be 3 538 kg (7,800 lbs).
You may go further and think the
tongue weight should be limited to
less than 454 kg (1,000 lbs) to avoid
exceeding GVWR. But the effect on
the rear axle must still be
considered. Because the rear axle
now weighs 1 406 kg (3,100 lbs),
408 kg (900 lbs) can be put on the
rear axle without exceeding
RGAWR. The effect of tongue
weight is about 1.5 times the actual
weight. Dividing the 408 kg (900 lbs)
by 1.5 leaves only 272 kg (600 lbs)
of tongue weight that can be
handled. Since tongue weight is
usually at least 10 percent of total
loaded trailer weight, expect that
the largest trailer the vehicle can
properly handle is 2 722 kg
(6,000 lbs).It is important that the vehicle
does not exceed any of its
ratings
—GCWR, GVWR, RGAWR,
Maximum Trailer Rating or Tongue
Weight. The only way to be sure it is
not exceeding any of these ratings
is to weigh the vehicle and trailer.
Total Weight on the Vehicle's
Tires
Inflate the vehicle's tires to the
upper limit for cold tires. These
numbers can be found on the
Certification label or see Vehicle
Load Limits
on page 9‑12for more
information. Do not go over the
GVW limit for the vehicle, or the
GAWR, including the weight of the
trailer tongue. If using a weight
distributing hitch, do not go over the
rear axle limit before applying the
weight distribution spring bars.
Towing Equipment
Hitches
It is important to have the correct
hitch equipment. Crosswinds, large
trucks going by and rough roads are
a few reasons why the right hitch is
needed.
.The rear bumper on the vehicle
is not intended for hitches. Do
not attach rental hitches or other
bumper-type hitches to it. Use
only a frame-mounted hitch that
does not attach to the bumper.
.Will any holes be made in the
body of the vehicle when the
trailer hitch is installed? If there
are, then be sure to seal the
holes when the hitch is removed.
If the holes are not sealed, dirt,
water, and deadly carbon
monoxide (CO) from the exhaust
may get into the vehicle. See
Engine Exhaust on page 9‑22.

9-54 Driving and Operating
Weight-Distributing Hitches and
Weight Carrying Hitches
A. Body-to-Ground Distance
B. Front of Vehicle
When using a weight-distributing
hitch, the hitch must be adjusted so
that the distance (A) remains the
same both before and after coupling
the trailer to the tow vehicle.
Safety Chains
Always attach chains between the
vehicle and the 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.
Always leave just enough slack so
the rig can turn. Never allow safety
chains to drag on the ground.
Trailer Brakes
A loaded trailer that weighs more
than 450 kg (1,000 lbs) needs to
have its own brake system that is
adequate for the weight of the
trailer. Be sure to read and follow
the instructions for the trailer brakes
so they are installed, adjusted and
maintained properly.
Because the vehicle has antilock
brakes, do not try to tap into the
vehicle's hydraulic brake system.
If you do, both brake systems will
not work well, or at all.
Trailer Wiring Harness
Basic Trailer Wiring
The trailer wiring harness, with a
seven-pin connector, is located at
the rear of the vehicle and is tied to
the vehicle's frame. The harness
connector can be plugged into a
seven-pin universal heavy-duty
trailer connector available through
your dealer/retailer.
The seven-wire harness contains
the following trailer circuits:
.Yellow: Left Stop/Turn Signal
.Dark Green: Right Stop/Turn
Signal
.Brown: Taillamps
.Black: Ground
.Light Green: Back-up Lamps
.Red/Black: Battery Feed
.Dark Blue: Trailer Brake*
*The fuse for this circuit is installed
in the underhood electrical center,
but the wires are not connected.