System Description [08/2015 - ]

1. The pre-collision system optimizes and activates occupant protection equipment (see below) to attempt to reduce damage due to a collision.
2. The operation of this system can be disabled by pressing and holding the pre-collision system cancel switch assembly.

   HINT: 

   When the pre-collision system is disabled, a warning message is displayed on the multi-information display for 6 seconds and the PCS warning indicator will be illuminated.

3. The operation of the pre-collision brake assist and pre-collision brake control are disabled when the VSC system is disabled.

   HINT: 

   When the pre-collision brake assist and pre-collision brake control are disabled, a warning message will be displayed on the multi-information display for approximately 6 seconds and the PCS warning indicator will be illuminated.

1. When operating according to sensor detection:

   The millimeter wave radar sensor detects vehicles and other objects on the road in front of the user's vehicle. The Driving Support ECU Assembly determines if a collision is unavoidable based on obstacle position, vehicle speed and road surface condition. If the Driving Support ECU Assembly determines that a collision is unavoidable, it transmits this information to the following areas using CAN communication:

   • Brake booster with master cylinder (skid control ECU) (activates pre-collision brake assist system)
   • Brake booster with master cylinder (skid control ECU) (activates pre-collision brake)
2. When operating as a result of sudden braking:

   The brake booster with master cylinder (skid control ECU) uses brake pressure information and other data to determine if the driver has suddenly applied the brakes.

1. When the system determines that there is a high possibility of colliding with an obstacle in front of the vehicle the multi-information display and warning buzzer are used to warn the driver and help with collision avoidance.

1. The pre-collision brake assist operates depending on what the sensor detects. The system then enters standby mode before a collision. When the driver depresses the brake pedal, brake fluid pressure is increased to improve fluid pressure response and improve the rate of deceleration.
2. Operative condition
   1. Refer to the sensor description under "Outline of Pre-Collision System" (see above).
   2. When the driver depresses the brake pedal after the Driving Support ECU Assembly determines that a collision is high possibility:

      Brake fluid pressure is increased at the same time the driver depresses the brake pedal.

   3. When the driver depresses the brake pedal before the Driving Support ECU Assembly determines that a collision is unavoidable:

      Brake fluid pressure is increased at the same time that the Driving Support ECU Assembly receives a pre-collision sensor signal (indicating that other vehicles or objects are in front of the vehicle).

1. The pre-collision brake operation is performed depending on what the sensor detects. This system can be canceled by the pre-collision system cancel switch assembly.

   HINT: 

   While the pre-collision brake operation is canceled, the PCS indicator light on the combination meter turns on.

2. Operating condition
   1. Refer to the sensor description under "Outline of Pre-Collision System" (see above).
   2. When the driving support ECU assembly determines that a collision is unavoidable, the system performs brake control (pre-collision brake operation) to reduce the vehicle speed.

1. Each time the switch is pressed, the sensitivity display on the multi-information display changes between "Far", "Middle" and "Near", and the sensitivity of the pre-collision system is changed to the displayed level.

   HINT: 

   • The sensitivity display on the multi-information display is displayed for 6 seconds.
   • "Middle" is the default setting.
   Fig 1: Identifying Pre-Collision System Sensitivity Switching Function

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *a	Far	*b	Middle
   *c	Near	-	-

1. When the switch is pressed and held for 3 seconds, the pre-collision system is canceled.

   HINT: 

   When the pre-collision system is canceled, a warning message will be displayed on the multi-information display and the PCS warning indicator will be illuminated.

HINT: 

Each function will operate when all items marked (◦) are satisfied.

• *: Does not operate in the following situations.
  • When the vehicle collides with an object outside the detection range of the millimeter wave radar sensor (side collision, rear collision, etc.)
  • When the millimeter wave radar sensor cannot detect a possible collision object
• ◦: Main basis for operation
• -: Not main basis for operation

1. When the millimeter wave radar sensor assembly detects an object in front of the vehicle under the following conditions, the driving support ECU assembly may determine that the possibility of a collision is high or a collision is unavoidable, and activate the pre-collision system. This activation of the system is not abnormal.
   Fig 2: Identifying Cases Of Unnecessary Pre-Collision System Operation

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *a	There are objects on the side of the road at the beginning of a curve (a guardrail, street lamp, billboard, etc.).	*b	Passing an oncoming vehicle on a curve.
   *c	There is an oncoming vehicle when making a left turn.	*d	Crossing a narrow metal bridge.
   *e	There are metal objects on the road.	*f	Approaching a leading vehicle suddenly.
   *g	Approaching an electrical toll collection gate (reacts to bar).	*h	Crossing an overpass, traffic sign, signboard
   *i	The vehicle height drastically changes (nose-up, nose-down).	*j	Misalignment of millimeter wave radar sensor assembly (reinstallation, collision, etc).
   *k	There is a billboard or sign at the top of an incline.	*l	There are metal objects at the bottom of a decline (a metal plate covering road construction, a mesh drain cover, a manhole, etc.).
   *m	Roughness in road surface.	*n	When passing through a tunnel.
   *o	The front of the vehicle is inclined (due to towing a trailer or another vehicle, or carrying a heavy load).	-	-

   HINT: 

   • The pre-collision system will not activate when approaching safety cones or other plastic objects as they cannot be detected by the millimeter wave radar sensor assembly.
   • The pre-collision system may or may not activate when the millimeter wave radar sensor assembly detects the following objects: people, bicycles, motorcycles, trees, animals, snow fences, etc.
   • Detection performance may deteriorate under the following conditions.
     • On a tight curve or bumpy road
     • Something or someone suddenly emerges in the direction of travel of the driver's vehicle at a place such as an intersection
     • Another vehicle suddenly cuts in the traveling direction of the driver's own vehicle
     • In severe weather such as heavy rain, fog, snow or a sand storm
     • Vehicle is skidding sideways while the electronically controlled brake system is not operating
     • Vehicle height changes significantly (front of vehicle inclined either upward or downward)
     • Millimeter wave radar sensor assembly is misaligned (due to reinstallation or collision)
     • An obstacle suddenly appears in front of the vehicle due to the steering wheel being turned sharply, etc.

       Object Type	Example
       Objects that cannot be detected	Plastic items (safety cones)
       Objects that cannot be detected in a stable manner	People, bicycles, motorcycles, trees, animals, snow fences, etc.