Pre-Collision System (Diagnostics - Introduction): Other Lexus LX J200

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 condition of the vehicle 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 ECUs, sensors, switches or other pre-collision system related parts, perform the following: Make sure the engine switch is off unless otherwise specified in the inspection procedures. After the removal/installation, check for DTCs and confirm that a normal system code is output.

Scheme 80

Scheme 81

Scheme 82

COMMUNICATION TABLE

Scheme 83

1. PRE-COLLISION SYSTEM The pre-collision system optimizes and activates occupant protection equipment in an attempt to reduce injury in a collision.
2. OUTLINE OF PRE-COLLISION SYSTEM Operating Condition Control Transmitting ECU Receiving ECU Part Operated Operates according to sensor detection Pre-collision seat belts Distance control ECU Seat belt control ECU Front seat outer belts Operates according to sensor detection Pre-collision brake assist Distance control ECU Master cylinder solenoid (skid control ECU) Brake assist system Operates when sudden braking occurs Pre-collision seat belts Master cylinder solenoid (skid control ECU) Seat belt control ECU Front seat outer belts When operating according to sensor detection: The distance control ECU uses information from the millimeter wave radar sensor to determine if the pre-collision system should be activated. If so, the distance control ECU sends signals to the master cylinder solenoid (skid control ECU) and seat belt control ECU through CAN communication. In response to these signals, the pre-collision system operates as follows: The seat belt control ECU initiates control of the pre-collision seat belts. The master cylinder solenoid (skid control ECU) activates the pre-collision brake assist system. When operating as a result of sudden braking: The master cylinder solenoid (skid control ECU) uses brake pressure information and other data to determine if the driver has suddenly applied the brakes. If so, the master cylinder solenoid (skid control ECU) sends a signal to the seat belt control ECU through CAN communication and the pre-collision seat belt activates.
3. OUTLINE OF PRE-COLLISION SEAT BELT CONTROL Pre-collision seat belt operation conditions: The driver firmly depresses the brake pedal suddenly. The driver oversteers or the vehicle is spinning. Pre-collision seat belt non-operation conditions: If any of the following conditions are met, the pre-collision seat belt does not operate. The seat belts are not fastened. The engine switch is off or on (ACC). The vehicle speed is approximately 30 km/h (18.6 mph) or less. When the pre-collision seat belts are repeatedly operated and the seat belt control ECU overheats, seat belt operation is prohibited to protect the ECU. HINT: The PCS warning indicator light in the combination meter will blink at this time.
4. OUTLINE OF PRE-COLLISION BRAKE ASSIST SYSTEM The pre-collision 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-collision 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-collision sensor signal (indicating that other vehicles or objects are in front of the vehicle).
5. OPERATIVE CONDITION AND INOPERATIVE CONDITION OF EACH CONTROL (REVIEW) Pre-collision Seat Belts*1 Pre-collision Seat Belts*2 Pre-collision Brake Assist*2 When the engine switch is off or on (ACC). - - - When a warning message is displayed on the multi-information display. *3 *3 *3 When the seat belt(s) is/are fastened. *4 *4 o Operates when the vehicle speed is 30 km/h (18.6 mph) or more, regardless of relative speed. o - - Operates when the vehicle speed is 5 km/h (3 mph) or more and relative speed is 30 km/h (18.6 mph). - o - Operates when the vehicle speed is 30 km/h (18.6 mph) or more and relative speed is 30 km/h (18.6 mph). - - o When the vehicle collides with an object outside the detection range of the millimeter wave radar sensor (side collision, rear collision, etc.). *5 - - When the millimeter wave radar sensor cannot detect a possible collision object. *5 - - HINT: *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 a seat belt is fastened *5: Pre-collision seat belts may operate when brakes are suddenly applied
6. PRECAUTION FOR PRE-COLLISION 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-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 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.

FAIL-SAFE CHART

1. The pre-collision system fail-safe function and details are indicated in the table below. Cause Warning Message Fail-safe Operation Conditions to Return to Normal Condition Malfunction exists in part of pre-collision system "Check PCS System" or "PCS Not available now" Depending on the malfunctioning part, the pre-collision seat belts or the brake assist system may stop operating.*1 Repair the malfunctioning part Radiator grille or millimeter wave radar sensor is dirty "PCS Not available now" Depending on the amount of dirt on the radiator grille or millimeter wave radar sensor, the pre-collision seat belts or the brake assist system may stop operating.*1 Clean the radiator grille or millimeter wave radar sensor Pre-collision sensor cannot detect possible crash object because of bad weather, such as snow "PCS Not available now" Depending on the amount of dirt on the radiator grille, the pre-collision seat belts or the brake assist system may stop operating.*1 Sensor can detect an object Overheating prevention function of seat belt control ECU operates*2 "PCS Not available now" The pre-collision seat belts may stop operating. Temperature of the seat belt goes down, and the seat belt control ECU becomes operative HINT: *1: The pre-collision seat belts operate only with sudden braking. *2: The overheating prevention function operates when the seat belt control ECU detects a rise in seat belt control ECU temperature because of excessive seat belt operation.