sensor TOYOTA SIENNA HYBRID 2023 Repair Manual

3294-5. Using the driving support systems
4
Driving
*: If equipped
This function will operate in situations such as the following if an
object is detected in the traveling direction of the vehicle.
■When traveling at a low speed and the brake pedal is not
depressed, or is depressed late
Parking Support Brake fu nction (static objects)*
If the sensors detect a static object, such as a wall, in the t rav-
eling direction of the vehicle and the system determines that
a collision may occur due to the vehicle suddenly moving for-
ward due to an accidental accelerator pedal operation, the
vehicle moving the unintended direction due to the wrong
shift position being selected, or while parking or traveling at
low speeds, the system will operate to lessen the impact with
the detected static object and reduce the resulting damage.
Examples of function operation

3304-5. Using the driving support systems
■When the accelerator pedal is depressed excessively
■When the vehicle moves in the unintended direction due to
the wrong shift position being selected
 P.312
Types of sensors
WARNING
■To ensure the system can
operate properly
 P.314
■If the Parking Support Brake
function (static objects) oper-
ates unnecessarily, such as
at a railroad crossing
 P.327
■Notes when washing the vehi-
cle
 P.314

3324-5. Using the driving support systems
*: If equipped
This function will operate in situations such as the following if a vehi-
cle is detected in the traveling direction of the vehicle.
■When reversing, a vehicle is approaching and the brake pedal
is not depressed, or is depressed late
 P.304
■The Parking Support Brake
function (rear-crossing vehi-
cles) will operate when
The function will op erate when the
PKSB OFF indicator is not illumi-
nated ( P.93, 94) and a ll of the fol-
lowing conditions are met:
●Hybrid system output restriction
control
• The Parking Support Brake is
enabled.
• The vehicle speed is approxi-
Parking Support Brake function (rear-crossing
vehicles)*
If a rear radar sensor detects a vehicle approaching from the
right or left at the rear of the vehicle and the system deter-
mines that the possibility of a collision is high, this function
will perform brake control to reduce the likelihood of an
impact with the approaching vehicle.
Examples of function operation
Types of sensors
WARNING
■To ensure the system can
operate properly
 P.304

3364-5. Using the driving support systems
■VSC (Vehicle Stability Con-
trol)
Helps the driver to control skid-
ding when swerving suddenly or
turning on slippery road sur-
faces.
■Enhanced VSC (Enhanced
Vehicle Stability Control)
Provides cooperative control of
the ABS, TRAC, VSC and EPS.
Helps to maintai n directional
stability when swerving on slip-
pery road surfaces by con-
trolling steering performance.
■Trailer Sway Control
Helps the driver to control trailer
sway by selectively applying
brake pressure for individual
wheels and reducing driving
torque when trailer sway is
detected.
■TRAC (Traction Control)
Helps to maintain drive power
and prevent the drive wheels
from spinning when starting the
vehicle or accelerating on slip-
pery roads
■Active Cornering Assist
(ACA)
Helps to prevent the vehicle
from drifting to the outer side by
performing inner wheel brake
control when attempting to
accelerate while turning
■Hill-start assist control
Helps to reduce the backward movement of the vehicle when
starting on an uphill
■EPS (Electric Power Steer-
ing)
Employs an electric motor to
reduce the amount of effort
needed to turn the steering
wheel.
■E-Four (Electronic On-
Demand AWD system)
(AWD models)
Automatically controls the drive
system such as to front-wheel
drive or AWD (all wheel drive)
according to various running
conditions including normal driv-
ing, during cornering, on a
uphill, when starting off, during
acceleration, on a slippery roads
due to snow or rain, thus con-
tributing to stable operability and
driving stability.
■The Secondary Collision
Brake
When the SRS airbag sensor
detects a collision and the sys-
tem operates, the brakes and
brake lights are automatically
controlled to reduce the vehicle
speed and help reduce the pos-
sibility of further damage due to
a secondary collision.
■When the
TRAC/VSC/ABS/T railer Sway
Control systems are operating
The slip indicator light will flash
while the TRAC/VSC/ABS/Trailer
Sway Control systems are operat-
ing.

3384-5. Using the driving support systems
■Sounds and vibrations caused
by the ABS, brake assist, VSC,
TRAC, Trailer Sway Control and
hill-start assist control systems
●A sound may be heard from the
engine compartment when the
brake pedal is dep ressed repeat-
edly, when the hybrid system is
started or just after the vehicle
begins to move. This sound does
not indicate that a malfunction has
occurred in any of these systems.
●Any of the following conditions
may occur when t he above sys-
tems 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 also after the vehicle comes to a stop.
■ECB operating sound
ECB operating sound may be heard
in the following cases, but it does
not indicate that a malfunction has
occurred.
●Operating sound heard from the
engine compartment when the
brake pedal is operated.
●Motor sound of the brake system
heard from the front part of the
vehicle when the driver’s door is
opened.
●Operating sound heard from the
engine compartment when one or
two minutes passed after the stop
of the hybrid system.
■Active Cornering Assist opera-
tion sounds and vibrations
When the Active Cornering Assist is
operated, operation sounds and
vibrations may b e generated from
the brake system, but this is not a
malfunction.
■EPS operation sound
When the steering wheel is oper-
ated, a motor sou nd (whirring
sound) may be heard. This does not
indicate a malfunction.
■Automatic reactivation of
TRAC, Trailer Sway Control and
VSC systems
After turning the TRAC, Trailer
Sway Control and VSC systems off,
the systems will be a utomatically re-
enabled in the following situations:
●When the power switch is turned
off
●If only the TRAC sy stem is turned
off, the TRAC will turn on when
vehicle speed increases
If both the TRAC and VSC sys-
tems are turned of f, automatic re-
enabling will not occur when vehi-
cle speed increases.
■Operating conditions of Active
Cornering Assist
The system operates when the fol-
lowing occurs.
●TRAC/VSC can operate
●The driver is attempting to accel-
erate while turning
●The system detects that the vehi-
cle is drifting to the outer side
●The brake pedal is released
■Reduced effectiveness of the
EPS system
The effect iveness of the EPS sys-
tem is reduced to prevent the sys-
tem from overheating when there is
frequent steering input over an
extended period of time. The steer-
ing wheel may feel heavy as a
result. Should this occur, refrain
from excessive steering input or
stop the vehicle a nd turn the hybrid
system off. The EPS system should
return to normal within 10 minutes.
■Secondary Collision Brake
operating conditions
The system operates when the SRS
airbag sensor de tects a collision
while the vehicle is in motion. How-
ever, the system does not operate
when the components are dam-
aged.

3976-1. Maintenance and care
6
Maintenance and care
wheels when they are hot, such
as after driving or parking in hot
weather
■Brake pads and calipers
Rust may form if the vehicle is
parked with wet brake pads or disc
rotors, causing them to stick. Before
parking the vehicle after it is
washed, drive slow ly and apply the
brakes several times to dry the
parts.
■Bumpers
Do not scrub with abrasive cleaners.
■Plated portions
If dirt cannot be removed, clean the
parts as follows:
●Use a soft cloth dampened with
an approximately 5% solution of
neutral detergent and water to
clean the dirt off.
●Wipe the surface with a dry, soft
cloth to remove any remaining
moisture.
●To remove oily deposits, use alco-
hol wet wipes or a similar product.
WARNING
■When washing the vehicle
Do not apply water to the inside of
the engine compartment. Doing
so may cause the electrical com-
ponents, etc. to catch fire.
■When cleaning the windshield
(vehicles with rain-sensing
windshield wipers)
Set the wiper switch to off.
If the wiper switch is in “AUTO”,
the wipers may operate unexpect-
edly in the following situations,
and may result in hands being
caught or other serious injuries
and cause damage to the wiper
blades.
Off
AUTO
●When the upper part of the
windshield where the raindrop
sensor is located is touched by
hand
●When a wet rag or similar is
held close to the raindrop sen-
sor
●If something bumps against the
windshield
●If you directly touch the raindrop
sensor body or if something
bumps into the ra indrop sensor
■Precautions regarding the
exhaust pipes
Exhaust gasses cause the
exhaust pipes to become quite
hot.
When washing the vehicle, be
careful not to touch the pipes until
they have cooled sufficiently, as
touching hot exhaust pipes can
cause burns.
A
B

4677-2. Steps to take in an emergency
7
When trouble arises
■PCS warning light (warning buzzer)
■LTA indicator (warning buzzer)
■Intuitive parking assist OFF indicator (warning buzzer)
Warning lightDetails/Actions
(Flashes or illumi-
nates)
When a buzzer sounds simultaneously:
Indicates a malfunction has occurred in the PCS (Pre-
Collision System).
 Have the vehicle insp ected by your Toyota
dealer immediately.
When a buzzer does not sound:
The PCS (Pre-Collision System) has become tempo-
rarily unavailable, correctiv e action may be necessary.
 Follow the instructions d isplayed on the multi-
information display. ( P.268, 478)
If the PCS (Pre-Collision S ystem) or VSC (Vehicle Sta-
bility Control) syst em is disabled, the PCS warning
light will illuminate.
 P.277
Warning lightDetails/Actions
(Orange)
Indicates a malfunction in the LTA (Lane Tracing
Assist)
Follow the instructions d isplayed on the multi-
information display. ( P.288)
Warning lightDetails/Actions
(If equipped)
When a buzzer sounds:
Indicates a malfunction in t he Intuitive parking assist
function
 Have the vehicle insp ected by your Toyota
dealer immediately.
When a buzzer does not sound:
Indicates that the system i s temporarily unavailable,
possibly due to a sensor bei ng dirty or covered with
ice, etc.
 Follow the instructions d isplayed on the multi-
information display. ( P.314, 475)

4687-2. Steps to take in an emergency
■RCD OFF indicator (warning buzzer)
■PKSB OFF indicator (warning buzzer)
■RCTA OFF indicator (warning buzzer)
Warning lightDetails/Actions
(If equipped)
When a buzzer sounds:
Indicates a malfunction in the RCD (Rear Camera
Detection) function
 Have the vehicle insp ected by your Toyota
dealer immediately.
When a buzzer does not sound:
Indicates that the function temporarily cannot be used
due to the camera being dirty, etc.
 Follow the instructions d isplayed on the multi-
information display. ( P.322, 475)
Warning lightDetails/Actions
(If equipped)
When a buzzer sounds:
Indicates a malfun ction in the PKSB ( Parking Support
Brake) system
 Have the vehicle insp ected by your Toyota
dealer immediately.
When a buzzer does not sound:
Indicates that the system i s temporarily unavailable,
possibly due to a sensor bei ng dirty or covered with
ice, etc.
 Follow the instructions d isplayed on the multi-
information display. ( P.328, 475)
Warning lightDetails/Actions
(If equipped)
When a buzzer sounds:
Indicates a malfunction in t he RCTA (Rear Cross Traf-
fic Alert) function
 Have the vehicle insp ected by your Toyota
dealer immediately.
When a buzzer does not sound:
Indicates that the rear bumper around the radar sen-
sor is covered with dirt, etc. (P.304)
 Follow the instructions d isplayed on the multi-
information display. ( P.304, 475)

4717-2. Steps to take in an emergency
7
When trouble arises
■Seat belt reminder light (warning buzzer*)
*: Driver’s seat belt warning buzzer:
The driver’s seat belt warning buzzer sounds to alert the drive r that his or
her seat belt is not fastened. Onc e the power switch is turned to ON, the
buzzer sounds. If the seat belt is still unfastened, the buzzer sounds inter-
mittently for a certain period o f time after the vehicle reaches a certain
speed.
Front passenger’s seat belt warning buzzer:
The front passenger’s seat belt warning buzzer sounds to alert the front
passenger that his or her seat belt is not fastened. If the sea t belt is
unfastened, the buzzer sounds int ermittently for a certain period of time
after the vehicle reaches a certain speed.
■Rear passengers’ seat belt reminder light (warning buzzer*)
*: Rear passengers’ seat belt warning buzzer:
The rear passengers’ seat belt warning buzzer sounds to alert t he rear
passengers that his or her seat belt is not fastened. If the se at belt is
unfastened, the buzzer sounds int ermittently for a certain period of time,
after the seat belt is fastened and unfastened and the vehicle reaches a
certain speed.
■Warning buzzer
In some cases, the buzzer may not
be heard because of noisy place or
an audio sound.■Front passenger detection sen-
sor, seat belt reminder and
warning buzzer
●If luggage is placed on the front
passenger seat, the front passen-
ger detection sensor may cause
the warning light to flash and the
warning buzzer to sound even if a
passenger is not sitting in the
Warning lightDetails/Actions
Warns the driver and/or front passenger to fasten their
seat belts
 Fasten the seat belt.
If the front passenger’s seat is occupied, the
front passenger’s seat belt also needs to be fas-
tened to make the warning light (warning
buzzer) turn off.
Warning lightDetails/Actions
Warns the rear passengers to fasten their seat belts
 Fasten the seat belt.

4727-2. Steps to take in an emergency
seat.
●If a cushion is placed on the seat,
the sensor may not detect a pas-
senger, and the warning light may
not operate properly.
■SRS warning light
This warning light system monitors
the airbag sensor assembly, front
impact sensors, side impact sensors
(front door), side impact sensors
(front), side impact sensors (rear),
driver’s seat position sensor,
driver’s seat belt buckle switch, front
passenger occupant classification
sensors, “AIR BAG ON” indicator
light, “AIR BAG OFF” indicator light,
front passenger’s seat belt buckle
switch, seat belt pretensioners and
force limiters, airbags, interconnect-
ing wiring and power sources.
(  P.42)
■If the malfunction indicator
lamp comes on while driving
First check the following:
●Is the fuel t ank empty?
If it is, fill the fuel tank immediately.
●Is the fuel tank cap loose?
If it is, tighten it securely.
The light will go o ff after several
driving trips.
If the light does not go off even after
several trips, contact your Toyota
dealer as soon as possible.
■Electric power steering system
warning light (warning buzzer)
When the 12-volt battery charge
becomes insufficien t or the voltage
temporarily drops, the electric power
steering system warning light may
come on and the warning buzzer
may sound.
■When the tire pressure warning
light comes on
Inspect the tires to check if a tire is
punctured.
If a tire is punctured: P.490 If none of the tires are punctured:
Turn the power switch to OFF then
turn it to ON.
Check if the tire pressure warning
light comes on or blinks.
If the tire pressur
e warning light
blinks for approximately 1 minute
then stays on
There may be a malfunction in the
tire pressure warning system. Have
the vehicle inspected by your
Toyota dealer immediately.
If the tire pressur e warning light
comes on
1 After the temperature of the tires
has lowered sufficiently, check
the inflation pressure of each tire
and adjust them to the specified
level.
2 If the warning light does not turn
off even after several minutes
have elapsed, check that the
inflation pressure of each tire is
at the specified level and perform
initialization. ( P.427)
■The tire pressure warning light
may come on due to natural
causes
The tire pressure warning light may
come on due to natural causes such
as natural air leaks and tire inflation
pressure changes caused by tem-
perature. In this ca se, adjusting the
tire inflation pressure will turn off the
warning ligh t (after a few minutes).
■When a tire is replaced with a
compact spare tire (vehicles
with compact spare tire)
The compact spare tire is not
equipped with a tire pressure warn-
ing valve and tran smitter. If a tire
goes flat, the tire pressure warning
light will not turn off even though the
flat tire has been replaced with the
spare tire. Replac e the spare tire
with the standard tire and adjust the
tire inflation pressure. The tire pres-
sure warning light will go off after a
few minutes.