Pre-Collision (Diagnostics - Introduction): Other Lexus HS I

PRECAUTION

1. TROUBLESHOOTING PRECAUTIONS If a terminal contact point malfunction or part installation problem occurs, removal and reinstallation of the suspected part may return the system to normal. However, be aware that the normal condition may only be temporary. Before disconnecting connectors or removing/installing parts, determine the malfunctioning area by checking and writing down the vehicle condition at the time of the malfunction (DTC outputs etc.). Be sure to check for DTCs related to other systems. The pre-collision system may be influenced by malfunctions in other systems.
2. HANDLING PRECAUTIONS When removing and installing the ECU, sensor, switch or other pre-collision system related parts, perform the following: Make sure the power switch is off unless otherwise specified in the inspection procedure. After the removal/installation, check for DTCs and confirm that a normal system code is output.

Scheme 62

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COMMUNICATION TABLE

Scheme 67

1. PRE-COLLISION SAFETY SYSTEM DESCRIPTION The pre-collision safety system detects vehicles and obstacles in front of the vehicle and performs the following: 1) optimally uses system controls to avoid crashes, and 2) uses system controls to reduce impact during a crash.
2. PRE-COLLISION DETECTION OUTLINE Pre-collision detection The driving support ECU receives information about vehicles and obstacles in front of the vehicle from the millimeter wave radar sensor assembly and lane recognition camera sensor assembly. Then, based on vehicle speed, road conditions and obstacle location, the driving support ECU determines, in advance, the risk of a crash and if a crash is unavoidable. The driver monitor camera detects the direction that the driver's head is facing. When a potential crash is detected and the camera determines that the driver's head is not facing forward, it activates the pre-collision alarm controls in advance. If the possibility of collision is high and the driving attitude/conditions have not improved, the ECU will initiate warning control. Sudden braking detection The brake booster with master cylinder (skid control ECU) activates the pre-collision safety seat belts when it detects sudden braking. Sudden braking is determined based on brake oil pressure and other information from the master cylinder pressure sensor. Vehicle control impossible judgment The pre-collision safety seat belts are activated when it is determined that there is a high probability that the vehicle cannot be controlled. The judgment is based on vehicle stability information from the yaw rate sensor and steering angle sensor. Component Component Detection Content Millimeter wave radar sensor Front object Lane recognition camera Front object Driver monitor camera Driver face direction
3. PRE-COLLISION SAFETY SYSTEM CONTROL DESCRIPTION Operation Condition Controls Sender ECU Receiver ECU Part Operated Front crash detection Crash is possible Pre-collision alarm Driving support ECU Combination meter Brake booster with master cylinder (skid control ECU) Combination meter Skid control buzzer Crash is unavoidable Pre-collision seat belts Driving support ECU Seat belt control ECU Front seat outer belts Crash is possible Crash is unavoidable Pre-collision brake assist Pre-collision brake Warning control Driving support ECU Brake booster with master cylinder (skid control ECU) Brake assist system Brake actuator Sudden braking detected Pre-collision seat belts Brake booster with master cylinder (skid control ECU) Seat belt control ECU Front seat outer belts Vehicle control impossible judgment Pre-collision seat belts Brake booster with master cylinder (skid control ECU) Seat belt control ECU Front seat outer belts
4. PRE-COLLISION ALARM CONTROL When the system determines that there is a risk 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 crash avoidance.
5. PRE-COLLISION SEAT BELT CONTROL When the system determines that a crash with an obstacle is unavoidable, that sudden braking has occurred, or that vehicle control is impossible, the system performs seat belt control. During seat belt control, slack in the seat belts is reduced, contributing to improved occupant safety.
6. PRE-COLLISION BRAKE ASSIST CONTROL When the system determines that there is a risk of colliding with an obstacle in front of the vehicle, brake assist is set to standby mode. Then, when the driver depresses the brake pedal, the hydraulic brake pressure is increased to improve braking effectiveness.
7. PRE-COLLISION BRAKE CONTROL When the system determines that a crash with an obstacle is unavoidable, the system performs brake control to reduce the vehicle speed.
8. PRE-COLLISION BRAKE CANCEL SWITCH When the pre-collision brake cancel switch in the glove box is turned on, the pre-collision alarm and pre-collision brake do not operate. HINT: While the pre-collision brake cancel switch is on, the combination meter PCS indicator light blinks.
9. PRE-COLLISION SAFETY SYSTEM OPERATING CONDITION Vehicle Condition Pre-collision Alarm Pre-collision Seat Belt*1 (Linked with Vehicle Tilt and Sudden Brake Operation) Pre-collision Seat Belt*2 (Linked with Radar) Pre-collision Brake Assist Pre-collision Brake Power switch off or on (ACC) X X X X X When warning message is displayed on multi-information display *1 *1 *1 *1 *1 When seat belt(s) are fastened o *2 *2 o o When own vehicle speed is 15km/h (9 mph) or more, regardless of relative speed X o X X X When own vehicle speed is 30 km/h (18 mph) or more and relative speed is 15 km/h (9 mph) X X X X o When own vehicle speed is 5 km/h (3 mph) or more and relative speed is 30 km/h (18 mph) X X o X X Regardless of own vehicle speed, when relative speed of other vehicle is 10 to 90 km/h (6 to 56 mph), and rear-end full lap or rear-end 50% offset collision occurs X X X X o When vehicle collides with object outside detection range of millimeter wave radar sensor (side collision, rear-end collision, etc.) X *3 X X X When millimeter wave radar sensor cannot detect possible collision object X *3 X X X When own vehicle speed is 30 km/h (18 mph) or more , and relative speed of other vehicle is 30 km/h (18 mph) or more X X X o X Pre-collision brake cancel switch on X o o o X HINT: o: Operation X: No operation *1: Inoperative parts are different depending on malfunction areas *2: Only operates when seat belt is fastened *3: Pre-collision seat belts may operate when brakes are suddenly applied
10. PRECAUTION FOR FRONT MILLIMETER WAVE RADAR SENSOR AND OBJECT RECOGNITION CAMERA When the millimeter wave radar sensor and lane recognition camera detect an object in front of the vehicle under the conditions described below, the driving support ECU may determine that a collision is unavoidable, and activates the pre-collision safety system. However, this is not abnormal. HINT: The pre-collision safety system does not activate when the pre-collision sensor detects safety cones and other plastic objects. The pre-collision system may or may not activate when the pre-collision sensor detects the following objects: people, bicycles, motorcycles, trees, animals and snow fences. Object Type Example Object that cannot be detected Plastic items (safety cones) Object that cannot always be detected People, bicycles, motorcycles, trees, animals, snow fences, etc.

FAIL-SAFE CHART

HINT

The pre-collision system fail-safe function and details are indicated in the table below.

*1: The overheating prevention function operates when the seat belt control ECU detects a rise in seat belt temperature because of excessive seat belt operation.

*2: The pre-collision seat belts operate only with sudden braking.