System Description [12/2013 - 11/2016]

1. The pre-collision system detects vehicles and obstacles in front of the vehicle and performs the following: 1) optimally uses system controls to avoid collisions, and 2) uses system controls to reduce impact during a collision.
2. The operation of this system can be disabled by the pre-collision system cancel switch assembly.

   HINT: 

   While the pre-collision system is disabled, the PCS warning indicator on the combination meter assembly is illuminated.

3. The operation of the pre-collision brake assist and pre-collision brake control can be disabled by the VSC OFF switch.

   HINT: 

   When the pre-collision brake assist control and pre-collision brake control are disabled, the multi-information display will display "VSC System Switched Off. Pre-Collision Brake System Disengaged." for approximately 6 seconds and the PCS warning light on the combination meter assembly illuminates.

1. When operating according to millimeter wave radar sensor assembly detection:

   The millimeter wave radar sensor assembly detects vehicles and other objects on the road in front of the user's vehicle. The driving support ECU assembly determines if the possibility of a collision is high or if a collision is unavoidable based on object position, speed and track information. If the driving support ECU assembly determines that the possibility of collision is high or that a collision is unavoidable, it transmits this information to the following areas via CAN communication:

   • Combination meter assembly (warning message) (activates pre-collision alarm)
   • Millimeter wave radar sensor assembly (warning buzzer) (activates pre-collision alarm)
   • Brake actuator assembly (activates pre-collision brake assist)
   • Brake actuator assembly (activates pre-collision brake)

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 millimeter wave radar sensor assembly 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. Operating conditions
   1. Refer to the millimeter wave radar sensor assembly 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 the possibility of a collision is high:

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

1. The pre-collision brake operation is performed depending on what the millimeter wave radar sensor assembly detects.
2. Operating conditions
   1. Refer to the millimeter wave radar sensor assembly 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.

      When a preceding vehicle is detected, the system advances brake control (pre-collision brake operation) activation timing in order to increase speed reduction performance.

HINT: 

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

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 1: Unnecessary Pre-Collision System Operation

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *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

   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 vehicle stability control 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)

       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.