Toyota CH-R Service Manual: System Description

SYSTEM DESCRIPTION

PRE-COLLISION SYSTEM DESCRIPTION

(a) The pre-collision system uses the pre-collision alarm control, pre-collision brake assist control and pre-collision brake control to help avoid a collision or reduce the impact if it determines that the possibility of a collision is high or a collision is unavoidable based on the position and relative speed of a preceding vehicle.

PRE-COLLISION SYSTEM SENSOR DESCRIPTION

(a) The pre-collision system sensor receives information on vehicles and pedestrians in front of the vehicle from the millimeter wave radar sensor assembly and forward recognition camera and determines in advance the risk of collision and whether the collision can be avoided, based on the position and vehicle speed.

FUNCTION OF MAIN COMPONENTS

COMPONENTS

FUNCTION

Millimeter Wave Radar Sensor Assembly

  • Radiates millimeter radar waves forward and uses reflected waves to detect the distance to, direction of, and relative speed of objects in front of the vehicle.
  • Determines if the possibility of a collision is high or a collision is unavoidable based on the signals from each sensor and sends brake request signals to the skid control ECU.
  • Sends request signals to illuminate the warning lights, display related information on the multi-information display in the combination meter assembly and sound a buzzer.

Forward Recognition Camera

Captures images of the area in front of the vehicle and processes them to detect preceding vehicles or pedestrians and sends information to the millimeter wave radar sensor assembly.

Yaw Rate and Acceleration Sensor (Airbag sensor assembly)

Detects the yaw rate and acceleration of the vehicle and sends signals to the millimeter wave radar sensor assembly.

Steering Angle Sensor (Spiral Cable with Sensor Sub-assembly)

Detects the steering angle and direction and sends signals to the millimeter wave radar sensor assembly.

Vehicle Speed Sensor

Detects the wheel speed and sends signals to the skid control ECU.

Stop Light Switch Assembly

  • Detects the depression of the brake pedal and sends signals to the skid control ECU.
  • Illuminates the stop lights based on the pre-collision braking control operation signal from the skid control ECU.

Steering Pad Switch Assembly

  • Used to turn the pre-collision system on and off.
  • Can be used to change the pre-collision system sensitivity setting.

VSC OFF Switch (Electric Parking Brake Switch Assembly)

Disables the pre-collision brake assist control and pre-collision brake control if pressed and held.

Skid Control ECU (Brake Actuator Assembly)

  • Performs pre-collision brake control based on brake request signals from the millimeter wave radar sensor assembly.
  • Sends wheel speed signals to the millimeter wave radar sensor assembly.
  • Detects the brake request signal and sends a signal to the Stop light switch assembly.

Combination Meter Assembly

  • Displays the pre-collision system control status (ON/OFF) and warning timing.
  • During a system malfunction, warns the driver by displaying a message in the multiinformation display according to the nature of the problem in the system, illuminating the PCS warning light and sounding the pre-collision buzzer.

Pre-collision City Buzzer

Sounds to warn the driver when the pre-collision alarm control is operated.

OUTLINE OF PRE-COLLISION SYSTEM

(a) PRE-COLLISION ALARM:

(1) When the system determines that the possibility of a frontal collision is high, a buzzer will sound and a warning message will be displayed on the multi-information display to urge the driver to take evasive action.

(b) PRE-COLLISION BRAKE ASSIST:

(1) 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.

(c) PRE-COLLISION BRAKE:

(1) 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 collision is extremely high, the brakes are automatically applied to help avoid the collision or reduce the collision speed.

HINT:

  • The vehicle may creep after the pre-collision brake function has operated, the driver should depress the brake pedal as necessary.
  • If the accelerator pedal is being depressed strongly or the steering wheel is being turned, the system may determine that the driver is taking evasive action and possibly prevent the pre-collision brake function from operating.

PRE-COLLISION SYSTEM CONTROL OPERATION

Control Operation

Control

Operating Condition

Transmitting ECU

Receiving ECU

Part Operated

Pre-collision alarm

Possibility of a collision is high

Millimeter Wave Radar Sensor Assembly

Combination Meter Assembly

  • Combination Meter Assembly (warning message)
  • Pre-collision City Buzzer (warning buzzer)

Pre-collision brake assist

  • Possibility of a collision is high
  • The brake pedal is depressed

Millimeter Wave Radar Sensor Assembly

  • Combination Meter Assembly
  • Skid Control ECU (Brake Actuator Assembly)
  • Combination Meter Assembly (warning message)
  • Pre-collision City Buzzer (warning buzzer)
  • Skid Control ECU (Brake Actuator Assembly)

Pre-collision brake

Possibility of a collision is high

Millimeter Wave Radar Sensor Assembly

  • Combination Meter Assembly
  • Skid Control ECU (Brake Actuator Assembly)
  • Combination Meter Assembly (warning message)
  • Pre-collision City Buzzer (warning buzzer)
  • Skid Control ECU (Brake Actuator Assembly)

PRE-COLLISION SYSTEM OPERATION CONDITIONS

CONTROL OPERATION CONDITIONS FOR EACH SPECIFICATION

Pre-collision Alarm

Pre-collision Brake Assist (PBA)

Pre-collision Brake (PB)

  • The pre-collision system is ON.
  • The vehicle speed is approximately 10 km/h (7 mph) or more.
  • The relative speed to a preceding vehicle is approximately 10 km/h (7 mph) or more.
  • The relative speed to a pedestrian is approximately 80 km/h (50 mph) or less.
  • The pre-collision system is ON.
  • The VSC is enabled.
  • The vehicle speed is approximately 30 km/h (19 mph) or more.
  • The relative speed to a preceding vehicle is approximately 30 km/h (19 mph) or more.
  • The relative speed to a pedestrian is approximately 80 km/h (50 mph) or less.
  • The pre-collision system is ON.
  • The VSC is enabled.
  • The vehicle speed is approximately 10 km/h (7 mph) or more.
  • The relative speed to a preceding vehicle is approximately 10 km/h (7 mph) or more.
  • The relative speed to a pedestrian is approximately 80 km/h (50 mph) or less.
CONTROLS AVAILABLE FOR EACH SPECIFICATION (REFERENCE)

Pre-collision Alarm

Pre-collision Brake Assist (PBA)

Pre-collision Brake (PB)

Pedestrian Detection Function

Available

Available

Available

Available

Conditions under which the system may operate even if there is no possibility of a collision

(a) In some situations such as the following, the system may determine that there is a possibility of a frontal collision and operate.

  • When passing a vehicle or pedestrian
  • When changing lanes while overtaking a preceding vehicle
  • When overtaking a preceding vehicle that is changing lanes
  • When overtaking a preceding vehicle that is making a left/right turn
  • When passing a vehicle in an oncoming lane that is stopped to make a right/left turn
  • When driving on a road where relative location to vehicle ahead in an adjacent lane may change, such as on a winding road
  • When a preceding vehicle suddenly decelerates
  • If the front of the vehicle is raised or lowered, such as when the road surface is uneven or undulating
  • When approaching objects on the roadside, such as guardrails, utility poles, trees, or walls
  • When there is a vehicle, pedestrian, or object by the roadside at the entrance of a curve
  • When driving on a narrow path surrounded by a structure, such as in a tunnel or on an iron bridge
  • When there is a metal object (manhole cover, steel plate, etc.), steps, or a protrusion on the road surface or roadside
  • When a crossing pedestrian approaches very close to the vehicle
  • When passing through a place with a low structure above the road (low ceiling, traffic sign, etc.)
  • When passing under an object (billboard, etc.) at the top of an uphill road
  • When rapidly closing on an electric toll gate barrier, parking area barrier, or other barrier that opens and closes
  • When using an automatic car wash
  • When driving through or under objects that may contact the vehicle, such as thick grass, tree branches, or a banner
  • When the vehicle is hit by water, snow, dust, etc. from a vehicle ahead
  • When driving through steam or smoke
  • When there are patterns or paint on the road or a wall that may be mistaken for a vehicle or pedestrian
  • When driving near an object that reflects radio waves, such as a large truck or guardrail
  • When driving near a TV tower, broadcasting station, electric power plant, or other location where strong radio waves or electrical noise may be present

Situations in which the system may not operate properly

(a) In some situations such as the following, a vehicle may not be detected by the millimeter wave radar sensor assembly and forward recognition camera, preventing the system from operating properly:

  • If an oncoming vehicle is approaching your vehicle
  • If a vehicle ahead is a motorcycle or bicycle
  • When approaching the side of a vehicle
  • If a preceding vehicle has a small rear end, such as an unloaded truck
  • If a preceding vehicle has a low rear end, such as a low bed trailer
  • If a vehicle ahead is carrying a load which protrudes past its rear bumper
  • If a vehicle ahead has extremely high ground clearance
  • If a vehicle ahead is irregularly shaped, such as a tractor or side car
  • If the sun or other light is shining directly on a vehicle ahead
  • If a vehicle cuts in front of your vehicle or emerges from beside a vehicle
  • If a vehicle ahead makes an abrupt maneuver (such as sudden swerving, acceleration or deceleration)
  • When suddenly cutting behind a preceding vehicle
  • When a vehicle ahead is not directly in front of your vehicle
  • When driving in inclement weather such as heavy rain, fog, snow or a sandstorm
  • When the vehicle is hit by water, snow, dust, etc. from a vehicle ahead
  • When driving through steam or smoke
  • When driving in a place where the surrounding brightness changes suddenly, such as at the entrance or exit of a tunnel
  • When a very bright light, such as the sun or the headlights of oncoming traffic, shines directly into the forward recognition camera
  • When the surrounding area is dim, such as at dawn or dusk, or while at night or in a tunnel
  • After the engine 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 front of the vehicle is raised or lowered, such as when the road surface is uneven or undulating
  • If the wheels are misaligned
  • If a wiper blade is blocking the forward recognition camera
  • The vehicle is wobbling
  • The vehicle is being driven at extremely high speeds
  • When driving on a hill

(b) 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

(c) Some pedestrians such as the following may not be detected by the millimeter wave radar sensor assembly and forward recognition camera, preventing the system from operating properly:

  • Pedestrians shorter than approximately 100 cm (3.2 ft.) or taller than approximately 200 cm (6.5 ft.)
  • Pedestrians wearing oversized clothing (a rain coat, long skirt, etc.), making their silhouette 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 as their 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 behind a vehicle or a large object
  • Pedestrians who are extremely close to the side of the vehicle (outside rear view mirror, etc.)

If the PCS warning light flashes and a warning message is displayed on the multi-information display

HINT:

For details on the operation of the PCS warning light and displayed warning messages, refer to Diagnosis System.

Click here

(a) The pre-collision system may be temporarily unavailable or there may be a malfunction in the system.

(b) 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 millimeter wave radar sensor assembly or forward recognition camera or the area around either sensor is hot, such as in the sun
  • When the millimeter wave radar sensor assembly or forward recognition camera or the area around either sensor is cold, such as in an extremely cold environment
  • When the millimeter wave radar sensor assembly or front grille emblem is dirty or covered with snow, etc.
  • If the forward recognition camera is obstructed, such as when the hood is open or a sticker is attached to the windshield near the forward recognition camera
  • When the millimeter wave radar sensor assembly is performing beam axis alignment correction after detecting a misaligned beam axis.

If VSC is disabled

(a) If VSC is disabled, the pre-collision brake assist and pre-collision brake functions are also disabled.

(b) The PCS warning light will turn on and "VSC Turned Off Pre-collision Brake System Unavailable" will be displayed on the multi-information display.

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