Pre-Collision - Supplemental Restraint System: Other Lexus LS IV

PRECAUTION

1. NOTICE FOR INITIALIZATION NOTE: When disconnecting the cable from the negative (-) battery terminal, initialize the following system after the cable is reconnected. SYSTEM NAME REFERENCE System Name See procedure Navigation System (for DVD) «INITIALIZATION»(ref-349706-S07943075812009120800000) Advanced Parking Guidance System Power Trunk Lid System Rear Door Sunshade System
2. PRECAUTIONS FOR TROUBLESHOOTING If the malfunction is due to connectors being loosely connected, or improper installation of parts, reconnecting the connectors or removing and reinstalling the parts may temporarily or completely correct the problem. To determine the malfunctioning area, use DTCs, freeze frame data and other data to help determine conditions at the time of the malfunction. Write down the data before disconnecting connectors or removing and installing parts. The pre-collision system may be affected by malfunctions in other systems. Check for DTCs in other systems and, if present, troubleshoot those DTCs first.
3. SERVICE PRECAUTIONS For parts that do not have specific inspection methods, perform all removal and installation procedures with the engine switch off. After removal and installation of parts has been performed, check for DTCs and confirm that none are output.
4. PRECAUTIONS WHEN REPLACING DRIVING SUPPORT ECU If the driving support ECU has been replaced, turn the engine switch off --> on (IG) for 10 seconds --> off to perform the initialization.

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Communication table

COMMUNICATION CHART

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1. PRE-COLLISION SYSTEM DESCRIPTION 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. PRE-COLLISION DETECTION OUTLINE Front collision detection The driving support ECU receives information about vehicles and obstacles in front of the vehicle from the front millimeter wave radar sensor. Then, based on vehicle speed, the driving support ECU determines, in advance, the risk of a collision and if a collision is unavoidable. Sudden braking detection The skid control ECU activates the pre-collision 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 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 CHART Component Detection Content Front millimeter wave radar sensor Front object
3. PRE-CRASH SAFETY SYSTEM CONTROL DESCRIPTION PRE-CRASH SAFETY SYSTEM CONTROL DESCRIPTION Operation Condition Controls Transmitting ECU Receiving ECU Part Operated Front collision detected 1. Collision is possible Pre-collision seat belts Driving support ECU Seat belt control ECU Front seat outer belts Collision is possible Collision is unavoidable Pre-collision brake assist Driving support ECU Skid control ECU Brake assist system Collision is possible Collision is unavoidable Air suspension control Driving support ECU Suspension Control ECU Shock absorbers Sudden braking detected Pre-collision seat belts Skid control ECU Seat belt control ECU Front seat outer belts Vehicle control impossible judgment Pre-collision seat belts Skid control ECU Seat belt control ECU Front seat outer belts
4. PRE-COLLISION SEAT BELT CONTROL When the system determines that a collision 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 to increase occupant restraint and aid the pretensioner.
5. PRE-COLLISION BRAKE ASSIST CONTROL When the system determines that there is a risk of colliding with an obstacle in front of the vehicle, break assist is set to standby mode. Then, when the driver depresses the brake pedal, the hydraulic brake pressure is increased to improve braking effectiveness.
6. AIR SUSPENSION CONTROL When it is determined that there is a risk of colliding with an obstacle in front of the vehicle, the air suspension is operated to control the damping force, suppress nose diving and rolling, and support collision avoidance through steering.
7. PRE-COLLISION SYSTEM (PCS) OPERATING CONDITION PRE-COLLISION SYSTEM (PCS) OPERATING CONDITION CHART Vehicle Condition Pre-collision Seat Belt*1 Pre-collision Seat Belt*2 Pre-collision Brake Assist AVS Control Engine switch off or on (ACC) X X X X When warning message is display on multi-information display *1 *1 *1 *1 When seat belt is/are fastened *2 *2 o o When own vehicle speed is 15 km/h (9 mph) or more, regardless of relative speed o X X X When own vehicle speed is 30 km/h (19 mph) or more and relative speed is 30 km/h (19 mph) X X o X When own vehicle speed is 5 km/h (3 mph) or more and relative speed is 30 km/h (19 mph) X o X o When vehicle collides with object outside detection range of front millimeter wave radar sensor (side collision, rear collision, etc.) *3 X X X When front millimeter wave radar sensor cannot detect possible collision object *3 X X X HINT: o: Operation X: Not 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
8. PRECAUTION FOR FRONT MILLIMETER WAVE RADAR SENSOR When the front millimeter wave radar sensor detects an object in front of the vehicle under the conditions described below, the driving support ECU may determine that a collision is unavoidable, and activate the pre-collision system. However, this is not abnormal. HINT: The pre-collision system will 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 CHART 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

1. FAIL SAFE FUNCTION When a malfunction occurs in part of the pre-collision system, "Check PCS system" or "PCS not Available Now" is displayed on the multi-information display. Depending on the malfunction, the pre-collision system may stop operating. When the driving support ECU determines that obstacle recognition is not possible due to dirt on the radiator grille, or front millimeter wave radar sensor, or due to snow or other adverse conditions, "PCS not Available Now" is displayed on the multi-information display, and operation of systems not controlled by the seat belt control ECU are stopped. Also, when obstacle recognition becomes possible, the display stops and normal control returns. If seat belt control ECU overheating prevention function operates, "PCS not Available Now" is displayed on the multi-information display, and pre-collision seat belt control operation stops. Also, when the temperature drops and pre-collision seat belt control becomes possible, the display stops and normal control returns. If there is a malfunction in the object recognition camera or driver monitor camera, "Check PCS system" is displayed on the multi-information display, and only the front millimeter wave radar sensor is able to determine when there is a collision. However, the control operation does not stop.