Lexus IS250 IS220d GSE20 ALE20 - PRE-CRASH SAFETY
PRE-CRASH SAFETY SYSTEM - SYSTEM DESCRIPTION
| PRE-CRASH SAFETY SYSTEM |
The pre-crash safety system optimizes and activates occupant protection equipment (see below) to attempt to reduce damage due to a collision.
| OUTLINE OF PRE-CRASH SAFETY SYSTEM |
| Operating Condition | Control | Transmitting ECU | Receiving ECU | Part operated |
| Operates according to sensor detection | Pre-crash safety seat belts | Distance control ECU | Seat belt control ECU | Front seat outer belts |
| Operates according to sensor detection | Pre-crash safety brake assist | Distance control ECU | Skid control ECU | Brake assist system |
| Operates when sudden braking occurs | Pre-crash safety seat belts | Skid control ECU | Seat belt control ECU | Front seat outer belts |
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 distance control ECU determines if a collision is unavoidable based on object position, speed and track information. If the distance control ECU determines that a collision is unavoidable, it transmits this information to the following areas using CAN communication:
When operating as a result of sudden braking:
The skid control ECU uses brake pressure information and other data to determine if the driver has suddenly applied the brakes. If so, the skid control ECU sends a signal to the seat belt control ECU through CAN communication and the pre-crash safety seat belt activates.
| OUTLINE OF PRE-CRASH SAFETY SEAT BELT CONTROL |
The pre-crash safety seat belt operates depending on what the sensor detects, or whether sudden braking has occurred. The pre-crash safety seat belt motor tightens the seat belt to optimize occupant restraint performance.
Operative condition
Refer to the sensor and sudden braking descriptions under "outline of pre-crash safety system" (see above).
| OUTLINE OF PRE-CRASH SAFETY BRAKE ASSIST SYSTEM |
The pre-crash safety brake assist system 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 vehicle speed reduction rate.
Operative condition
Refer to the sensor description under "outline of pre-crash safety system" (see above).
When the driver depresses the brake pedal after the distance control ECU determines that a collision is unavoidable:
Brake fluid pressure is increased at the same time the driver depresses the brake pedal.
When the driver depresses the brake pedal before the distance control ECU determines that a collision is unavoidable:
Brake fluid pressure is increased at the same time that the distance control ECU receives a pre-crash safety sensor signal (indicating that other vehicles or objects are in front of the vehicle).
| OPERATIVE CONDITION AND INOPERATIVE CONDITION OF EACH CONTROL (REVIEW) |
| Pre-crash safety seat belts (*1) | Pre-crash safety seat belts (*2) | Pre-crash safety brake assist (*2) | |
| Engine switch off or on (ACC) | - | - | - |
| When a warning message is displayed on the multi-information display | *3 | *3 | *3 |
| When seat belt(s) is / are fastened | *4 | *4 | ○ |
| Operates when the vehicle speed is 30 km/h or more, regardless of relative speed | ○ | - | - |
| Operates when the vehicle speed is 5 km/h or more and relative speed is 30 km/h | - | ○ | ○ |
| 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 can not detect a possible collision object | ○ | - | - |
*1: Operates when brakes are suddenly applied.
*2: Operates according to sensor detection.
*3: Inoperative parts are different depending on malfunction areas.
*4: Only operates when seat belt is fastened.
| PRECAUTION FOR PRE-CRASH SAFETY SYSTEM OPERATION |
When the millimeter wave radar sensor detects an object in front of the vehicle under the conditions described below, the distance control ECU may determine that a collision is unavoidable, and activate the pre-crash safety system. This activation of the system is not abnormal.
- HINT:
| 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 fence, etc |