2018 VOLVO XC90 TWIN ENGINE brakes

STARTING AND DRIVING
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* Option/accessory. 445
Drive modes
Drive modes affect the vehicle's driving charac-
teristics in different ways to enhance and sim-
plify the driving experience in certain types of sit-
uations. Drive modes enable easy access to the vehicle's
many functions and settings in different driving
situations. The following systems are adapted to
help optimize driving characteristics in each drive
mode:
• Steering
• Engine/transmission/all-wheel drive
• Brakes
• Pneumatic suspension* and shock absorbers
• Instrument panel
• Climate control settings
Select the drive mode that is best suited to the
current driving conditions. Keep in mind that not
all drive modes are available in all situations.
Available drive modes
WARNING Keep in mind that the vehicle does not emit
any engine noise when using the electric
motor and may therefore be difficult to detect
for children, pedestrians, cyclists or animals.
This is particularly true at low speeds, e.g. in
parking lots.
WARNING
Do not leave the vehicle in an unventilated
area with a drive mode activated and the com-
bustion engine switched off. The engine will
start automatically if the charge level in the
hybrid battery is low and the resulting exhaust
gases can be very harmful to people and ani-
mals.
HYBRID
•
This is the default mode in which the electric
motor and combustion engine work together.
The vehicle starts in Hybrid mode. The control
system uses both the electric motor and the gas-
oline engine - separately or in tandem - and cal-
culates optimal utilization with regard to perform-
ance, fuel consumption and comfort. At high
speeds, ground clearance is automatically low-
ered 4
to reduce air resistance. Driving capacity on
the electric motor alone is determined by factors such as the hybrid battery's charge level, the
need for heat/cooling in the passenger compart-
ment, etc.
If there is sufficient charge in the battery, it is
possible to drive solely on electric power. When
the accelerator pedal is pressed, only the electric
motor will be activated until the battery reaches a
certain charge level. Above this level, the current
in the battery cannot supply the power requested
by the accelerator pedal and the combustion
engine will start.
When the hybrid battery's charge level is low, the
combustion engine will start more frequently to
save the remaining current in the battery. Charge
the hybrid battery from a 120-240 volt outlet
using a charging cable, or activate
Charge in
Function view to reset the option of only using
the electric motor.
This drive mode is designed for low energy con-
sumption with an optimized mix between the
electric motor and gasoline engine, without com-
promising on climate comfort or driving experi-
ence. When faster acceleration is requested by
the driver, the electric driveline will be utilized to
help provide maximum additional power. The
vehicle also monitors the driving conditions and
automatically engages all-wheel drive if neces-
sary. All-wheel drive and extra electric power are
always available regardless of the battery's
charging status. 4
For vehicles with pneumatic suspension.

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454
NOTE
When LSC with HDC is activated in the OFF
ROAD drive mode, the feel of the accelerator
pedal and engine response will change.
NOTE
This drive mode is not designed to be used
for normal street driving.
NOTE
The function is deactivated when driving at
high speeds and must be reactivated at lower
speeds if so desired.
Related information
•
Activating and deactivating Low Speed Con-
trol using the function button (p. 454)
• Changing drive mode (p. 449)
• Hill Descent Control (p. 454)
• All Wheel Drive (AWD) (p. 443) Activating and deactivating Low
Speed Control using the function
button
Vehicles that are not equipped with drive mode
controls in the tunnel console have a function
button for Low Speed Control with Hill Descent
Control in the center display's Function view.
Selecting Low Speed Control in the
center display's Function view
– Tap the Hill Descent Control button to
activate or deactivate the function. > An indicator light in the button will illumi-
nate when the function is activated.
When the engine is switched off, the function will
be automatically deactivated.
NOTE The function is deactivated when driving at
high speeds and must be reactivated at lower
speeds if so desired.
Related information
•
Low Speed Control (p. 453)
• Changing drive mode (p. 449) Hill Descent Control
The function for assisting when driving downhill,
Hill Descent Control (HDC), is a low-speed
function with increased engine braking. The
function makes it possible to increase or
decrease the vehicle's speed on steep downhill
gradients by only using the accelerator pedal,
without applying the brakes.
The function is included in the Off Road drive
mode.
HDC is designed for driving on rough roads at
low speeds and downhill gradients with slippery
or otherwise difficult road surfaces. The driver
does not need to use the brake pedal but can
instead focus on steering.
WARNING
HDC is only intended to be a supplementary
braking aid and it does not function in all sit-
uations.
The driver is always ultimately responsible for
operating the vehicle in a safe manner.
FunctionHill Descent Control allows the vehicle to move
forward or backward at very low speeds assisted
by the brake system. The driver can increase the
speed by pressing the accelerator pedal. When
the accelerator pedal is released, the vehicle will
return to very low speed regardless of how steep

STARTING AND DRIVING
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455
the hill is and without the brakes needing to be
applied. The brake lights will illuminate when the
function is activated.
The driver can brake to stop or slow the vehicle
at any time by depressing the brake pedal.
HDC is activated along with Low Speed Control
(LSC), which facilitates and improves traction and
control on rough and slippery surfaces. The sys-
tem is intended to be used at low speeds, up to
approximately 40 km/h (25 mph).
To keep in mind when using HDC
•
If the function is switched off while driving on
a steep downhill gradient, braking effect will
be gradually reduced.
• HDC can be used in gear positions D and R,
and in manual gears 1 or 2.
• It is not possible to manually shift to third
gear or higher when HDC is active.
NOTE When LSC with HDC is activated in the OFF
ROAD drive mode, the feel of the accelerator
pedal and engine response will change.
NOTE
This drive mode is not designed to be used
for normal street driving.
NOTE The function is deactivated when driving at
high speeds and must be reactivated at lower
speeds if so desired.
Related information
•
Activating and deactivating Hill Descent Con-
trol using the function button (p. 455)
• Changing drive mode (p. 449)
• Low Speed Control (p. 453)
• All Wheel Drive (AWD) (p. 443) Activating and deactivating Hill
Descent Control using the function
button
Vehicles that are not equipped with drive mode
controls in the tunnel console have a function
button for Hill Descent Control with Hill
Descent Control in the center display's Func-
tion view.
Selecting Hill Descent Control in the
center display's Function view
HDC only works at low speeds.
– Tap the
Hill Descent Control button to
activate or deactivate the function. > An indicator light in the button will illumi-
nate when the function is activated.
When the engine is switched off, the function will
be automatically deactivated.
NOTE The function is deactivated when driving at
high speeds and must be reactivated at lower
speeds if so desired.

STARTING AND DRIVING
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457
Driving
• Choose the Pure drive mode to help mini-
mize electric power consumption.
• Maintain a steady speed and a generous fol-
lowing distance to traffic ahead to minimize
braking. This drive mode has the lowest
power consumption.
• Balance energy requirements using the
accelerator pedal. Use the indicator on the
instrument panel to see available electric
power and avoid starting the combustion
engine unnecessarily. The electric motor is
more effective than the combustion engine,
especially at low speeds.
• When braking is necessary, brake gently
using the brake pedal. This will recharge the
hybrid battery. A regenerative function is
integrated in the brake pedal and can be
augmented by the electric motor's braking
capacity when the gear selector is in mode
B.
• Higher speeds increase energy consumption
- air resistance increases with speed.
• Activate the
Hold function in the Function
view at high speeds when traveling farther
than is possible using the hybrid battery's
capacity.
• Whenever possible, avoid using the Charge
function to charge the hybrid battery. Charg-
ing the battery using the combustion engine increases fuel consumption and carbon diox-
ide emissions.
• In a cold climate, reduce heating of the wind-
shield/rear window, mirrors, seats and the
steering wheel.
• Maintain the correct pressure in the tires and
check pressure regularly.
• The type of tires used could affect energy
consumption - consult a retailer for advice on
suitable tires.
• Remove unnecessary items from the vehicle
- the heavier the load, the higher the fuel
consumption.
• Roof loads increase air resistance and
increase fuel consumption. Remove roof
boxes, ski racks, etc. that are not in use.
• Avoid driving with the windows open.
• Do not keep the vehicle still on an upward
gradient by using the accelerator pedal. Use
the brakes instead.
Related information
•
Drive-E
‒
purer driving pleasure (p. 27)
• Factors affecting electric motor range
(p. 458)
• Using the electric motor only (p. 457)
• Hybrid gauge (p. 87)
• Checking tire pressure (p. 557) Using the electric motor only
When using the electric motor, Volvo Twin
Engine provides a combination of good fuel
economy, low emissions and high performance.
For energy-efficient driving:
• Select the Pure drive mode to help maximize
driving range using only the electric motor.
• Balance energy requirements using the
accelerator pedal. Use the indicator on the
instrument panel's hybrid gauge to see avail-
able electric power and avoid starting the
combustion engine unnecessarily.
• When braking is necessary, brake gently
using the brake pedal. This will recharge the
hybrid battery.
• Activate the
Hold function in the Function
view at high speeds when traveling farther
than is possible using the hybrid battery's
capacity.
• Reduce current consumption in the passen-
ger compartment by reducing e.g. fan speed,
electric heating, or air conditioning use.
Also follow the general economical driving advice
regarding speed, tires and load to maximize
range.
Related information
• General information about Twin Engine
(p. 406)
• Economical driving (p. 456)

STARTING AND DRIVING
462Driving through standing water
Driving the vehicle through a deep pool of stand-
ing water on a water-covered roadway is called
fording. This must be done with great caution. To prevent damage to the vehicle when driving
through water (e.g. on flooded roads):
• Do not drive in water higher than the floor of
the vehicle. If possible, check the depth of
the water at its deepest point before driving
through it. Be particularly careful when driv-
ing through flowing water.
• Always select the Off Road drive mode
before driving in water to ensure the gasoline
engine is running.
• Do not drive faster than walking speed.
• Do not stop the vehicle in the water. Drive
carefully forward or back the vehicle out of
the water.
• Remember that waves created by passing
vehicles could cause the water level to rise
above the vehicle's floor level.
• Avoid driving through salt water to help avoid
the risk of corrosion.
CAUTION Parts of the vehicle (e.g. engine, transmission,
driveline, electrical components, etc.) can be
damaged if the vehicle is driven through water
higher than its floor level. Damage to any
components caused by flooding, vapor lock or
insufficient oil is not covered under warranty.
If the engine stalls while the vehicle is in
water, do not attempt to restart it. Have the
vehicle towed on the bed of a tow truck to a
workshop - an authorized Volvo workshop is
recommended.
When you have passed the water, press lightly on
the brake pedal and check that the brakes are
functioning properly. Water, mud, slush, etc. can
make the brake linings slippery, resulting in
delayed braking effect.
If the vehicle is equipped with a trailer coupling
contact, clean the contact after driving in water or
mud.
Related information
•
Recovery (p. 477)
• Low Speed Control (p. 453) Opening/closing the fuel filler door
A button on the instrument panel is used to
unlock the fuel filler door.
An arrow next to the fuel pump
symbol in the instrument panel
indicates the side of the vehicle
on which the fuel filler door is
located.

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472
Stowing the ball holder
WARNING
When not in use, the detachable ball holder
should always be properly stowed in the des-
ignated location under the floor of the cargo
compartment.
Related information
•
Driving with a trailer (p. 472)
• Towing capacity and tongue weight (p. 660) Driving with a trailer
There are a number of things to consider when
towing a trailer, such as the towbar, the trailer
and how the load is distributed in the trailer.
Load-carrying capacity is determined by the vehi-
cle's curb weight. The total weight of all passen-
gers and any installed accessories, e.g. towbar,
reduces the vehicle's load-carrying capacity by
the corresponding amount.
• Towbars used on the vehicle must be
approved for the applicable use.
• Distribute the load on the trailer so that the
weight on the towbar complies with the
specified maximum towball weight. The
tongue weight is calculated as part of the
vehicle's payload.
• Increase the tire pressure to the recom-
mended pressure for a full load.
• The engine is subjected to more load than
usual when towing a trailer.
• Towing a trailer affects the vehicle's han-
dling, durability and driving economy.
• Do not drive with a heavy trailer when the
vehicle is very new. Wait until the mileage
has reached at least 1000 km (620 miles).
• On long and steep downgrades, the vehicle's
brakes are subjected to much more load
than usual. When manually shifting, down-
shift and adapt speed accordingly. •
Follow applicable regulations regarding per-
mitted speed and weight.
• Drive slowly when towing a trailer up a long
and steep incline.
• The maximum trailer weights given only apply
to altitudes up to 1000 meters (3280 feet)
above sea level. At higher altitudes, engine
power (and thus the vehicle's climbing ability)
is decreased due to the reduced air density,
and the maximum trailer weight must there-
fore be reduced. The weight of the vehicle
and trailer must be decreased by 10% for
each additional 1000 m (3280 feet) or part
thereof.
• Avoid driving with a trailer on inclines of more
than 12%.
• Avoid overloading and other incorrect use.
• The trailer's brakes must be balanced with
the vehicle's brakes to help ensure safe
stops (follow applicable local regulations).

STARTING AND DRIVING
* Option/accessory.
474 Trailer Stability Assist*
Trailer Stability Assist (TSA 8
) is a function
designed to help stabilize a vehicle that is tow-
ing a trailer when the vehicle and trailer have
begun to sway. The function is part of the Elec-
tronic Stability Control system ESC 9
.
Reasons for swayingA vehicle towing a trailer may begin to sway for
various reasons. Normally this only occurs at high
speeds. However, if the trailer is overloaded or
unevenly distributed, e.g. too far back, there is a
risk of swaying even at low speeds.
Swaying may be caused by factors such as:
• The vehicle and trailer are hit by a sudden,
strong crosswind.
• The vehicle and trailer are traveling on an
uneven road or over a bump.
• Sudden movements of the steering wheel.
Once swaying has begun, it can be difficult or
impossible to stop it. This makes the vehicle and
trailer difficult to control and there is a risk of
swerving into oncoming traffic or driving off the
road.
Trailer Stability Assist functionTrailer Stability Assist continuously monitors the
vehicle's movements, particularly lateral move- ments. If swaying is detected, the brakes are
applied individually on the front wheels, which has
a stabilizing effect on the vehicle and trailer. This
is often enough to enable the driver to regain
control of the vehicle.
If the Trailer Stability Assist function's first
attempt is not adequate to stop the swaying
motion, the brakes are applied on all wheels and
engine power is temporarily reduced. As the
swaying motion begins to decrease and the vehi-
cle and trailer have once again become stable,
TSA stops regulating the brakes/engine power
and the driver regains control of the vehicle.
NOTE
Trailer Stability Assist is deactivated if the
driver selects the sport mode by deactivating
ESC in the center display's menu system. Trailer Stability Assist may not intervene if the
driver tries to compensate for the swaying motion
by moving the steering wheel rapidly, because
the system will then not be able to determine if it
is the trailer or the driver causing the swaying. When Trailer Stability Assist is
activated, the ESC symbol is
displayed in the instrument
panel.
Related information
•
Driving with a trailer (p. 472)
• Electronic Stability Control (p. 274) 8
Trailer Stability Assist
9 Electronic Stability Control

||WHEELS AND TIRES
572
CAUTION
Snow chains can be used on the vehicle, with
the following restrictions:
• Volvo recommends not using snow
chains on wheel dimensions larger than
19 inches.
• Always follow the manufacturer's installa-
tion instructions carefully. Install chains
as tightly as possible and retighten peri-
odically.
• Only put snow chains on the front wheels
(also applies to all-wheel drive vehicles).
• If accessory, aftermarket or "custom"
tires and wheels with different dimen-
sions than the original tires and wheels
are used, snow chains in some cases
may NOT be used. Sufficient distance
between the chains and brakes, suspen-
sion and body components must be
maintained.
• Check local regulations regarding the use
of snow chains before installing.
• Never exceed the snow chain manufac-
turer's specified maximum speed limit.
Under no circumstances should you
exceed 50 km/h (30 mph).
• Avoid bumps, holes or sharp turns when
driving with snow chains. •
Avoid driving on surfaces without snow as
this wears out both the snow chains and
the tires.
• The handling of the vehicle can be
adversely affected when driving with
chains. Avoid fast or sharp turns as well
as locked wheel braking.
• Some types of strap-on chains affect
brake components and therefore must
NOT be used. Consult a Volvo retailer for more information
about snow chains.
Related information
•
Winter driving (p. 461) Tire sealing system
13
The temporary tire sealing system can be used
to seal a puncture in a tire or to check and
adjust the pressure in the tire.
Models equipped with a spare wheel 14
do not
have the tire sealing system.
The tire sealing system consists of a compressor
and a bottle containing sealing compound. The
sealing functions as a temporary repair.
NOTE The sealing compound effectively seals tires
with punctures in the tread but may not be
able to fully seal tires with punctures in the
sidewall. Do not use the tire sealing system
on tires with large tears, cracks or similar
damage.
NOTE
The compressor is intended for temporary tire
sealing and is approved by Volvo.
LocationThe tire sealing system is located in a foam block
under the floor of the cargo compartment.