brake LEXUS GS300H 2019 Service Manual

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The pre-crash safety system is equipped with a sophisticated computer that will
record certain data, such as:
• Accelerator status
• Brake status
• Vehicle speed
• Operation status of the pre-crash safety system functions
• Information (such as the distance and relative speed between your vehicle
and the vehicle ahead or other objects)
The pre-crash safety system does not record conversations, sounds or pictures.
●Data usage
Lexus may use the data recorded in this computer to diagnose malfunctions,
conduct research and development, and improve quality.
Lexus will not disclose the recorded data to a third party except:
• With the consent of the vehicle owner or with the consent of the lessee if
the vehicle is leased
• In response to an official request by the police, a court of law or a govern-
ment agency
• For use by Lexus in a lawsuit
• For research purposes where the data is not tied to a specific vehicle or
vehicle owner
Vehicle data recording

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PCS (Pre-Crash Safety system)
◆Pre-crash warning
When the system determines that
the possibility of a frontal collision is
high, a buzzer will sound and a warn-
ing message will be displayed on the
multi-information display to urge the
driver to take evasive action.
◆Pre-crash brake assist
When the system determines that the possibility of a frontal collision is high,
the system applies greater braking force in relation to how strongly the brake
pedal is depressed.
: If equipped
The pre-crash safety system uses a radar sensor and camera sensor to detect
vehicles and pedestrians*1 in front of your vehicle. When the system deter-
mines that the possibility of a frontal collision with a vehicle or pedestrian is
high, a warning operates to urge the dr iver to take evasive action and the
potential brake pressure is increased to help the driver avoid the collision. If
the system determines that the possibility of a frontal collision with a vehicle or
pedestrian is extremely high, the brakes are automatically applied*2 to help
avoid the collision or help reduce the impact of the collision.
The pre-crash safety system can be disabled/enabled and the warning timing
can be changed. ( P. 273)
*1: Depending on the region in which the vehicle was sold, the pedestrian detection
function may not be available. Contact any authorized Lexus retailer or Lexus
authorized repairer, or any reliable repairer for details.
*2: Depending on the region in which the vehicle was sold, the pre-crash braking func-
tion (automatic braking function) may not be available. Contact any authorized
Lexus retailer or Lexus authorized repair er, or any reliable repairer for details.

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◆Pre-crash braking*3
When the system determines that the possibility of a frontal collision is high,
the system warns the driver. If the system determines that the possibility of a
frontal collision is extremely high, the brakes are automatically applied to help
avoid the collision or reduce the collision speed.
*3: Depending on the region in which the vehicle was sold, the pre-crash braking function
may not be available.
◆Suspension control (if equipped)
When the system determines that the possibility of a frontal collision is high,
the Adaptive Variable Suspension System ( P. 325) will control the damping
force of the shock absorbers to help maintain an appropriate vehicle posture.
◆Steering control (if equipped)
When the system determines that the possibility of a frontal collision is high
and the driver is operating the steering wheel, the LDH system ( P. 325) will
control the turning angle of the front and rear wheels and effort necessary to
turn the steering wheel to help enhance steering responsiveness.
WARNING
■Limitations of the pre-crash safety system
●The driver is solely responsible for safe driving. Always drive safely, taking care to
observe your surroundings. Do not use the pre-crash safety system instead of normal braking operations underany circumstances. This system will not pr event collisions or lessen collision damage
or injury in every situation. Do not overly re ly on this system. Failure to do so may lead to an accident, resulting in death or serious injury.
●Although this system is designed to help avoid a collision or help reduce the impact of
the collision, its effectiveness may change according to various conditions, therefore the system may not always be able to achieve the same level of performance.
Read the following conditions carefully. Do not overly rely on this system and always drive carefully.
• Conditions under which the system may oper ate even if there is no possibility of a
collision: P. 276 • Conditions under which the system may not operate properly: P. 279
●Do not attempt to test the operation of the pre-crash safety system yourself, as the system may not operate properly, possibly leading to an accident.

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WARNING
■Pre-crash braking*3
●When the pre-crash braking function is operating, a large amount of braking force will be applied.
●If the vehicle is stopped by the operation of the pre-crash braking function, the pre-crash braking function operation will be canceled after approximately 2 seconds.Depress the brake pedal as necessary.
●The pre-crash braking function may not operate if certain operations are performedby the driver. If the accelerator pedal is being depressed strongly or the steeringwheel is being turned, the system may determine that the driver is taking evasive
action and possibly prevent the pre-crash braking function from operating.
●In some situations, while the pre-crash braking function is operating, operation of thefunction may be canceled if the accelerator pedal is depressed strongly or the steer-
ing wheel is turned and the system determines that the driver is taking evasive action.
●If the brake pedal is being depressed, the system may determine that the driver is tak-ing evasive action and possibly delay the operation timing of the pre-crash braking
function.
*3: Depending on the region in which the vehicle was sold, the pre-crash braking func-
tion may not be available.
■When to disable the pre-crash safety system
In the following situations, disable the system, as it may not operate properly, possibly
leading to an accident resulting in death or serious injury:
●When the vehicle is being towed
●When your vehicle is towing another vehicle
●When transporting the vehicle via truck, boat, train or similar means of transportation
●When the vehicle is raised on a lift with the hybrid system on and the tires are allowed to rotate freely
●When inspecting the vehicle using a drum tester such as a chassis dynamometer orspeedometer tester, or when using an on vehicle wheel balancer
●When a strong impact is applied to the front bumper or front grille, due to an accident
or other reasons
●If the vehicle cannot be driven in a stable manner, such as when the vehicle has beenin an accident or is malfunctioning
●When the vehicle is driven in a sporty manner or off-road
●When the tires are not properly inflated
●When the tires are very worn
●When tires of a size other than specified are installed
●When tire chains are installed
●When a compact spare tire or an emergency tire puncture repair kit is used
●If equipment (snow plow, etc.) that may obstruct the radar sensor or camera sensor istemporarily installed to the vehicle

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■Operational conditions
Availability of the pedestrian detection func tion and pre-crash braking function depend on the region in which the vehicle was sold.
Read the following for details:
Region A (The pedestrian detection function and pre-crash braking function are available)
The pre-crash safety system is enabled and th e system determines that the possibility of a
frontal collision with a vehicle or pedestrian is high.
Each function is operational at the following speeds:
●Pre-crash warning:
• Vehicle speed is between approximately 10 and 180 km/h (7 and 110 mph). (For detecting a pedestrian, vehicle speed is between approximately 10 and 80 km/h [7and 50 mph].)
• The relative speed between your vehicle and the vehicle or pedestrian ahead is approximately 10 km/h (7 mph) or more.
●Pre-crash brake assist:
• Vehicle speed is between approximately 30 and 180 km/h (19 and 110 mph). (For detecting a pedestrian, vehicle speed is between approximately 30 and 80 km/h
[19 and 50 mph].) • The relative speed between your vehicle and the vehicle or pedestrian ahead isapproximately 30 km/h (19 mph) or more.
●Pre-crash braking:
• Vehicle speed is between approximately 10 and 180 km/h (7 and 110 mph). (For
detecting a pedestrian, vehicle speed is between approximately 10 and 80 km/h [7 and 50 mph].)• The relative speed between your vehicle and the vehicle or pedestrian ahead is
approximately 10 km/h (7 mph) or more. The system may not operate in the following situations:
●If a 12-volt battery terminal has been disconnected and reconnected and then the vehi-
cle has not been driven for a certain amount of time
●If the shift lever is in R
●If VSC is disabled (only the pre-cras h warning function will be operational)
●If the PCS warning light is flashing or illuminated
RegionsFunction availability
Region AThe pedestrian detection function and pre-crash braking func- tion are available
Region BThe pedestrian detection function is not available and the pre-crash braking function is available
Region CThe pedestrian detection function and pre-crash braking func-
tion are not available

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Region B (The pedestrian detection function is not available and the pre-crash braking functionis available)
The pre-crash safety system is enabled and th e system determines that the possibility of a frontal collision with a vehicle is high.
Each function is operational at the following speeds:
●Pre-crash warning:
• Vehicle speed is between approximately 15 and 180 km/h (10 and 110 mph). • The relative speed between your vehicle and the vehicle ahead is approximately
10 km/h (7 mph) or more.
●Pre-crash brake assist:
• Vehicle speed is between approximately 30 and 180 km/h (19 and 110 mph). • The relative speed between your vehicle and the vehicle ahead is approximately30 km/h (19 mph) or more.
●Pre-crash braking:
• Vehicle speed is between approximately 15 and 180 km/h (10 and 110 mph).
• The relative speed between your vehicle and the vehicle ahead is approximately 10 km/h (7 mph) or more.The system may not operate in the following situations:
●If a 12-volt battery terminal has been disconnected and reconnected and then the vehi-cle has not been driven for a certain amount of time
●If the shift lever is in R
●If VSC is disabled (only the pre-cras h warning function will be operational)
●If the PCS warning light is flashing or illuminated
Region C
(The pedestrian detection function and pre-crash braking function are not available)
The pre-crash safety system is enabled and th e system determines that the possibility of a
frontal collision with a vehicle is high.
Each function is operational at the following speeds:
●Pre-crash warning:
• Vehicle speed is between approximately 15 and 180 km/h (10 and 110 mph). • The relative speed between your vehicle and the vehicle ahead is approximately10 km/h (7 mph) or more.
●Pre-crash brake assist:
• Vehicle speed is between approximately 30 and 180 km/h (19 and 110 mph).
• The relative speed between your vehicle and the vehicle ahead is approximately 30 km/h (19 mph) or more.The system may not operate in the following situations:
●If a battery terminal has been disconnected and reconnected and then the vehicle hasnot been driven for a certain amount of time
●If the shift lever is in R
●If VSC is disabled (only the pre-cras h warning function will be operational)
●If the PCS warning light is flashing or illuminated

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• After the hybrid system has started the vehicle has not been driven for a certain amount of time• While making a left/right turn and for a few seconds after making a left/right turn
• While driving on a curve and for a few seconds after driving on a curve • If your vehicle is skidding
• If the wheels are misaligned • If a wiper blade is blocking the camera sensor
• The vehicle is wobbling. • The vehicle is being driven at extremely high speeds.• When driving on a hill
• If the radar sensor or camera sensor is misaligned
●In some situations such as the following, sufficient braking force may not be obtained,
preventing the system from performing properly:
• If the braking functions cannot operate to their full extent, such as when the brake parts are extremely cold, extremely hot, or wet
• If the vehicle is not properly maintained (brakes or tires are excessively worn, improper tire inflation pressure, etc.)• When the vehicle is being driven on a gravel road or other slippery surface
●Some pedestrians such as the following may not be detected by the radar sensor and
camera sensor, preventing the system from operating properly*4:
• Pedestrians shorter than approximately 1 m (3 .2 ft.) or taller than approximately 2 m
(6.5 ft.) • Pedestrians wearing oversized clothing (a rain coat, long skirt, etc.), making their sil- houette obscure
• Pedestrians who are carrying large baggage, holding an umbrella, etc., hiding part of their body• Pedestrians who are bending forward or squatting
• Pedestrians who are pushing a stroller , wheelchair, bicycle or other vehicle • Groups of pedestrians which are close together• Pedestrians who are wearing white and look extremely bright
• Pedestrians in the dark, such as at night or while in a tunnel • Pedestrians whose clothing appears to be nearly the same color or brightness astheir surroundings
• Pedestrians near walls, fences, guardrails, or large objects • Pedestrians who are on a metal object (manhole cover, steel plate, etc.) on the road• Pedestrians who are walking fast
• Pedestrians who are changing speed abruptly • Pedestrians running out from be hind a vehicle or a large object • Pedestrians who are extremely close to the side of the vehicle (outside rear view
mirror, etc.)
• If the front of the vehicle is raised or low- ered

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*4: Depending on the region in which the vehicle was sold, the pedestrian detection
function may not be available.
■If the PCS warning light flashes and a warnin g message is displayed on the multi-infor- mation display
The pre-crash safety system may be temporar ily unavailable or there may be a malfunc-
tion in the system.
●In the following situations, the warning light will turn off, the message will disappear and the system will become operational when normal operating conditions return:
• When the radar sensor or camera sensor or the area around either sensor is hot, such as in the sun• When the radar sensor or camera sensor or the area around either sensor is cold,
such as in an extremely cold environment • When the radar sensor or front grille emblem is dirty or covered with snow, etc.• When the part of the windshield in front of the camera sensor is fogged up or cov-
ered with condensation or ice (Defogging the windshield: P. 352) • If the camera sensor is obstructed, such as when the hood is open or a sticker isattached to the windshield near the camera sensor
●If the PCS warning light continues to flash or the warning message does not disappear,the system may be malfunctioning. Have the vehicle inspected by any authorized Lexus
retailer or Lexus authorized repairer, or any reliable repairer immediately.
■If VSC is disabled
●If VSC is disabled (P. 327), the pre-crash brake assist and pre-crash braking func-
tions are also disabled.
●The PCS warning light will turn on and “VSC Turned Off Pre-Crash Brake System Unavailable” will be displayed on the multi-information display.

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This mode employs a radar sensor to detect the presence of vehicles up to
approximately 100 m (328 ft.) ahead, determines the current vehicle-to-vehicle
following distance, and operates to maintain a suitable following distance from
the vehicle ahead.
Note that vehicle-to-vehicle distance will close in when traveling on long downhill slopes.
Example of constant speed cruising
When there are no vehicles ahead
The vehicle travels at the speed set by the driver. The desired vehicle-to-vehicle dis- tance can also be set by operating the vehicle-to-vehicle distance button.
Example of deceleration cruising and follow-up cruising
When a preceding vehicle driving slower than the set speed appears
When a vehicle is detected running ahead of you, the system automatically deceler- ates your vehicle. When a greater reduction in vehicle speed is necessary, the systemapplies the brakes (the stop lights will come on at this time). The system will respond to
changes in the speed of the vehicle ahead in order to maintain the vehicle-to-vehicle distance set by the driver. Approach wa rning warns you when the system cannot decelerate sufficiently to prevent your vehicle from closing in on the vehicle ahead.
When the vehicle ahead of you stops, your ve hicle will also stop (vehicle is stopped by system control). After the vehicle ahead starts off, pushing the cruise control lever upor depressing the accelerator pedal will resume follow-up cruising.
Example of acceleration
When there are no longer any preceding vehicles driving slower than the set
speed
The system accelerates until the set speed is reached. The system then returns to con-
stant speed cruising.
Driving in vehicl e-to-vehicle distance control mode
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Pulling the lever toward you cancels
the speed control.
The speed control is also canceled when
the brake pedal is depressed.
(When the vehicle has been stopped by system control, depressing the brake
pedal does not cancel the setting.)
Pushing the lever up resumes the
cruise control and returns vehicle
speed to the set speed.
However, when a vehicle ahead is not detected, cruise control does not resume when the vehicle speed is approximately 40 km/h (25 mph) or less.
When your vehicle is too close to a
vehicle ahead, and sufficient automatic
deceleration via the cruise control is
not possible, the display will flash and
the buzzer will sound to alert the driver.
An example of this would be if another
driver cuts in front of you while you are
following a vehicle. Depress the brake
pedal to ensure an appropriate vehicle-
to-vehicle distance.
■Warnings may not occur when
In the following instances, warnings may not occur even when the vehicle-to-
vehicle distance is small.
●When the speed of the preceding vehicle matches or exceeds your vehicle
speed
●When the preceding vehicle is traveling at an extremely slow speed
●Immediately after the cruise control speed was set
●When depressing the accelerator pedal
Canceling and resuming the speed control
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Approach warning (vehicle-to- vehicle distance control mode)