Pre-Collision System (Diagnostics - Introduction): Other Lexus GX J150

PRECAUTION

1. PRECAUTIONS FOR TROUBLESHOOTING If a 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 output, troubleshoot those DTCs first.

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Scheme 178

COMMUNICATION TABLE

1. *1: w/ Air Suspension
2. *2: w/ Driver Monitor Camera
3. *3: w/ Lane Departure Alert System

Scheme 179

1. PRE-COLLISION SYSTEM DESCRIPTION The pre-collision system detects vehicles and obstacles in front of the vehicle and performs the following: 1) the system uses the multi-information display and sounds a buzzer to warn the driver of a collision and prompt preventive action, 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 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 possibility of a collision and if a collision is unavoidable. *: w/ Lane Departure Alert System w/ Driver Monitor Camera: The driver monitor camera detects the direction that the driver's head is facing. When a potential collision is detected and the camera determines that the driver's head is not facing forward, the driver monitor ECU activates the pre-collision controls in advance. If the possibility of a collision increases and the driver's head is still not facing forward, warning brake control operates. 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 Detection Content Millimeter wave radar sensor assembly Front object Lane recognition camera sensor assembly*1 Front object Driver monitor camera*2 Driver facial direction *1: w/ Lane Departure Alert System *2: w/ Driver Monitor Camera
3. PRE-COLLISION SYSTEM CONTROL DESCRIPTION Operation Condition Control Sender ECU Receiver Part Operated Front collision detection Collision is possible Pre-collision alarm Driving support ECU Combination meter assembly Combination meter assembly Skid control ECU Skid control buzzer Collision is unavoidable 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 Pre-collision brake 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 absorber 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 *: w/ Air Suspension
4. PRE-COLLISION ALARM CONTROL When the system determines that there is a possibility of a collision 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. w/ Driver Monitor Camera: When the system determines that there is a possibility of a collision with an obstacle in front of the vehicle, the system warns the driver to help prevent a collision by displaying messages in the multi-information display in the combination meter assembly, sounding the buzzer and illuminating the PCS indicator light. When the system determines that there is a possibility of a collision and the driver monitor camera detects that the driver's head is not facing forward for a specified period of time, the warnings are performed earlier than normal.
5. 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 aid the pretensioner.
6. PRE-COLLISION BRAKE ASSIST CONTROL When the system determines that there is a possibility 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. AIR SUSPENSION CONTROL (w/ Air Suspension) When it is determined that there is a possibility of colliding with an obstacle in front of the vehicle, the AVS is operated to control the damping force, suppress nose diving and rolling, and support collision avoidance through steering.
8. PRE-COLLISION BRAKING CONTROL When the system determines that a collision with an obstacle is unavoidable, the system performs brake control to reduce the vehicle speed.
9. PRE-COLLISION BRAKE CANCEL SWITCH ASSEMBLY When the pre-collision brake cancel switch assembly in the No. 1 instrument panel under cover sub-assembly is turned on, the pre-collision alarm and pre-collision brake do not operate. HINT: While the pre-collision brake cancel switch assembly is on, the PCS indicator light in the combination meter assembly illuminates.
10. PRE-COLLISION SYSTEM OPERATING CONDITION Vehicle Condition Pre-collision Alarm Pre-collision Seat Belt (Linked with Understeer or Oversteer Tendency Operation and Sudden Brake Operation) Pre-collision Seat Belt (Linked with Radar) Pre-collision Brake Assist Pre-collision Braking Air Suspension Control*4 Engine switch off or on (ACC) X X X X X X Pre-collision brake cancel switch assembly is on X o o o X o Warning message is displayed on multi-information display *1 *1 *1 *1 *1 *1 Seat belt(s) are fastened *2 o o *2 *2 o Vehicle speed is 30 km/h (18 mph) or more, regardless of relative speed X o X X X X Vehicle speed is 15 km/h (9 mph) or more and relative speed is 15 km/h (9 mph) X X X X o o Vehicle speed is 5 km/h (3 mph) or more and relative speed is 30 km/h (18 mph) X X o X X o Vehicle speed is 30 km/h (18 mph) or more and relative speed is 30 km/h (18 mph) X X X o X X Vehicle collides with object outside detection range of millimeter wave radar sensor assembly X *3 X X X X Millimeter wave radar sensor assembly cannot detect possible collision object X *3 X X X X Vehicle speed is 15 km/h (9 mph) or more, regardless of relative speed o X X X X X Relative speed is 15 km/h (9 mph) or more, regardless of vehicle speed o X X X X X Relative speed is 40 km/h (24 mph) or more, regardless of vehicle speed*5 o X X X X X Driver monitor camera determines that driver's head is not facing forward for specified period of time*5 o X X X X X HINT: o: Operates X: Does not operate *1: Inoperative functions are different depending on malfunction areas *2: Operates regardless of whether the seat belts are fastened or not *3: Pre-collision seat belts may operate when brakes are suddenly applied *4: w/ Air Suspension *5: w/ Driver Monitor Camera
11. PRECAUTION FOR MILLIMETER WAVE RADAR SENSOR AND LANE RECOGNITION CAMERA SENSOR ASSEMBLY* *: w/ Lane Departure Alert System When the millimeter wave radar sensor assembly and lane recognition camera sensor* 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 activate the pre-collision system. However, this is not abnormal. HINT: The pre-collision system is not activated by safety cones and other plastic objects which cannot be detected by the millimeter wave radar sensor assembly and lane recognition camera sensor assembly*. The pre-collision system may or may not be activated by the following objects which cannot always be detected by the millimeter wave radar sensor assembly and lane recognition camera sensor assembly*: people, bicycles, motorcycles, trees, animals, snow fences, etc. Object Type Example Object that cannot be detected Safety cones, plastic items 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 TEMPORARILY NOT AVAILABLE" 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 millimeter wave radar sensor assembly, or due to snow or other adverse conditions, "PCS TEMPORARILY NOT AVAILABLE" is displayed on the multi-information display and operation of systems except pre-collision seat belt control operation linked with understeer or oversteer tendency operation and sudden brake control are stopped. When obstacle recognition becomes possible, the display stops and normal control returns. If the overheating protection function of the seat belt control ECU or millimeter wave radar sensor assembly operates, "PCS TEMPORARILY NOT AVAILABLE" is displayed on the combination meter assembly and pre-collision seat belt control stops. When the temperature drops and pre-collision system operation is possible, the display turns off and normal control returns. If a malfunction occurs in the lane recognition camera sensor or driver monitor camera, "CHECK PCS SYSTEM" is displayed on the multi-information display and collision judgment is performed using only the millimeter wave radar sensor assembly.