2012 TOYOTA SIENNA Owners Manual

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2-4. Using other
driving systems
2
When driving
SIENNA_U (OM45477U)
Disabling TRAC and VSC system
If the vehicle gets stuck in fresh snow or mud, TRAC and VSC may
reduce power from the engine to the wheels. You may need to turn
the system off to enable you to rock the vehicle in order to free it.
■ Turning off the TRAC system only
To turn the TRAC system off,
quickly press and release the
button.
The “TRAC OFF” indicator light
will come on.
Push the button again to turn the
system back on.
■Turning off both TRAC and VSC systems
To turn the TRAC and VSC sys-
tems off, press and hold the but-
ton for more than 3 seconds
while the vehicle is stopped.
The “TRAC OFF” indicator light
and VSC OFF indicator light will
come on.
Press the button again to turn the
systems back on.

330 2-4. Using other driving systems
SIENNA_U (OM45477U)
■When the “TRAC OFF” indicator light comes on even if the VSC OFF
switch has not been pressed
TRAC and hill-start assist control cannot be operated. Contact your Toyota
dealer.
■ Sounds and vibrations caused by ABS, brake assist, Enhanced VSC
and TRAC
● A sound may be heard from the engine compartment when the engine is
started or just after the vehicle begins to move. This sound does not indi-
cate that a malfunction has occurred in any of these systems.
● Any of the following conditions may occur when the above systems are
operating. None of these indicates that a malfunction has occurred.
• Vibrations may be felt through the vehicle body and steering.
• A motor sound may be heard after the vehicle comes to a stop.
• The brake pedal may pulsate slightly after ABS is activated.
• The brake pedal may move down slightly after ABS is activated.
■ EPS operation sound
When the steering wheel is operated, a motor sound (whirring sound) may
be heard. This does not indicate a malfunction.
■ Reactivation of the TRAC and VSC systems after turning off the engine
Turning off the engine after turning off the TRAC and VSC systems will auto-
matically reactivate them.
■ Reactivation of the TRAC system linked to vehicle speed
When only the TRAC system is turned off, the TRAC system will turn on
when vehicle speed increases. However, when both TRAC and VSC sys-
tems are turned off, the systems will not turn on even when vehicle speed
increases.

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2-4. Using other
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When driving
SIENNA_U (OM45477U)
■Reduced effectiveness of the EPS system
The effectiveness of the EPS system is reduced to prevent the system from
overheating when there is frequent steering input over an extended period of
time. The steering wheel may feel heavy as a result. Should this occur,
refrain from excessive steering input or stop the vehicle and turn the engine
off. The EPS system should return to normal within 10 minutes.
CAUTION
■ABS does not operate effectively when
● Tires with inadequate gripping ability are used (such as excessively worn
tires on a snow covered road).
● The vehicle hydroplanes while driving at high speed on wet or slick roads.
■ Stopping distance when ABS is oper ating may exceed that of normal
conditions
The ABS is not designed to shorten the vehicle’s stopping distance. Always
maintain a safe distance from the vehicle in front of you in the following situ-
ations.
● When driving on dirt, gravel or snow-covered roads
● When driving with tire chains
● When driving over bumps in the road
● When driving over roads with potholes or roads with uneven surfaces
■ TRAC may not operate effectively when
Directional control and power may not be achievable while driving on slip-
pery road surfaces, even if the TRAC system is operating.
Do not drive the vehicle in conditions where stability and power may be lost.

332 2-4. Using other driving systems
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CAUTION
■When Enhanced VSC is activated
The slip indicator light flashes and a warning buzzer sounds. Always drive
carefully. Reckless driving may cause an accident. Exercise particular care
when the indicator light flashes and a buzzer sounds.
■ When TRAC and VSC systems are turned off
Be especially careful and drive at a speed appropriate to the road condi-
tions. As these are the systems to ensure vehicle stability and driving force,
do not turn the TRAC and VSC systems off unless necessary.
■ Replacing tires
Make sure that all tires are of the specified size and of the same brand, tread
pattern and total load capacity. In addition, make sure that the tires are
inflated to the recommended tire pressure level.
The ABS and Enhanced VSC systems will not function correctly if different
tires are installed on the vehicle.
Contact your Toyota dealer for further information when replacing tires or
wheels.
■ Handling of tires and suspension
Using tires with any kind of problem or modifying the suspension will affect
the driving assist systems, and may cause the system to malfunction.
■ Active Torque Control 4WD system
● The AWD system of this vehicle is intended to ensure driving stability on
normal roads. It is not designed for use in demanding situations such as
rally driving.
● Take care when driving on slippery road surfaces.

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2-4. Using other driving systems
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When driving
SIENNA_U (OM45477U)
Hill-start assist control
: If equipped
Hill-start assist control helps to prevent the vehicle from rolling
backwards when starting on an incline or slippery slope.
To engage hill-start assist con-
trol, further depress the brake
pedal when the vehicle is
stopped completely.
A buzzer will sound once to
indicate that the system is acti-
vated. The slip indicator will
also start flashing.

334 2-4. Using other driving systems
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■Hill-start assist control can be operated when
• The shift lever is in a position other than P.
• The parking brake is not applied.
• The accelerator pedal is not depressed.
■ Hill-start assist control
● While hill-start assist control is operating, the brakes remain automati-
cally applied after the driver releases the brake pedal. The stop lights and
the high mounted stoplight turn on.
● Hill-start assist control operates for about 2 seconds after the brake pedal
is released.
● If the slip indicator does not flash and the buzzer does not sound when
the brake pedal is further depressed, slightly reduce the pressure on the
brake pedal (do not allow the vehicl e to roll backward) and then firmly
depress it again. If the system still does not operate, check if the operat-
ing conditions explained above have been met.
■ Hill-start assist control buzzer
● When hill-start assist control is activated, the buzzer will sound once.
● In the following situations, hill-start assist control will be canceled and the
buzzer will sound twice.
• No attempt is made to drive the vehicle within approximately 2 seconds
of releasing the brake pedal.
• The shift lever is moved to P.
• The parking brake is applied.
• The brake pedal is depressed again.
• The brake pedal has been depressed for more than approximately 3 minutes.
■ If the slip indicator comes on...
It may indicate a malfunction in the system. Contact your Toyota dealer.

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When driving
SIENNA_U (OM45477U)
CAUTION
■Hill-start assist control
● Do not overly rely on hill-start assist control. Hill-start assist control may
not operate effectively on extremely steep inclines or roads covered in ice.
● Unlike the parking brake, hill-start assist control is not intended to hold the
vehicle stationary for an extended period of time. Do not attempt to use
hill-start assist control to hold the vehicle on an incline for an extended
period of time, as doing so may lead to an accident.

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PCS (Pre-Collision System)
: If equipped
When the radar sensor detects that a frontal collision is highly likely
or even unavoidable, the systems such as the brakes and seat
belts are automatically engaged to lessen impact to occupants as
well as vehicle damage.
■ Pre-collision seat belts (front seat belts only)
If the pre-collision s ensor detects that a co llision is unavoidable,
the pre-collision system will retract the seat belt before the colli-
sion occurs. The same will happen if the driver makes an emer-
gency braking or loses co ntrol of the vehicle. (P. 131)
However, when the VSC system is disabled, the system will not
operate in the event of skidding.
■ Pre-collision brake assist
When there is a high possibility of a frontal collision, the system
applies greater braking force in relation to how strongly the
brake pedal is depressed.
■ Pre-collision braking
When there is a high possibility of a frontal collision, the system
warns the driver using a warning light and buzzer. If the system
determines that a collision is un avoidable, the brakes are auto-
matically applied to reduce th e collision speed. Pre-collision
braking can be disabled usi ng the pre-collision braking off
switch.