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

PRECAUTION

1. NOTICE FOR INITIALIZATION NOTE: When disconnecting the cable from the negative (-) auxiliary battery terminal, initialize the following systems after the cable is reconnected. System Name See Procedure Parking Assist Monitor System Refer to «INITIALIZATION»(ref-568589-S03492911652013072300000) Power Door Lock Control System
2. 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.
3. 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 296

Scheme 297

Scheme 298

COMMUNICATION TABLE

Scheme 299

1. PRE-COLLISION SYSTEM The pre-collision system optimizes and activates occupant protection equipment (see below) to attempt to reduce damage due to 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 belt Driving support ECU Seat belt control ECU Front seat outer belts Operates according to sensor detection Pre-collision brake assist Driving support ECU Brake booster with master cylinder (skid control ECU) Brake assist system Operates when sudden braking or sideways slippage occurs Pre-collision seat belt Brake booster with master cylinder (skid control ECU) Seat belt control ECU Front seat outer belts Operates according to sensor detection Pre-collision brake assist Driving support ECU Brake booster with master cylinder (skid control ECU) Brake system 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 driving support ECU determines if a collision is unavoidable based on object position, speed and track information. If the driving support ECU determines that a collision is unavoidable, it transmits this information to the following areas using CAN communication: Seat belt control ECU (initiates control of pre-collision seat belts) Brake booster with master cylinder (skid control ECU) (activates pre-collision brake assist system) Brake booster with master cylinder (skid control ECU) (activates pre-collision brake) When operating as a result of sudden braking: The brake booster with master cylinder (skid control ECU) uses brake pressure information and other data to determine if the driver has suddenly applied the brakes. If so, the brake booster with master cylinder (skid control ECU) sends a signal to the seat belt control ECU through CAN communication and the pre-collision seat belts activate.
3. OUTLINE OF PRE-COLLISION SEAT BELT CONTROL The pre-collision seat belts operate depending on what the sensor detects, or whether sudden braking has occurred. The pre-collision seat belt motor retracts the seat belt to enhance pretensioner effectiveness. Operative condition Refer to the sensor and sudden braking descriptions under "Outline of Pre-Collision System" (see above).
4. OUTLINE OF PRE-COLLISION BRAKE ASSIST CONTROL The pre-collision brake assist 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 the rate of deceleration. Operative condition Refer to the sensor description under "Outline of Pre-Collision System" (see above). When the driver depresses the brake pedal after the driving support 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 driving support ECU determines that a collision is unavoidable: Brake fluid pressure is increased at the same time that the driving support ECU receives a pre-collision sensor signal (indicating that other vehicles or objects are in front of the vehicle).
5. OUTLINE OF PRE-COLLISION BRAKE CONTROL The pre-collision brake operates depending on what the sensor detects. This system can be canceled by the pre-collision brake off switch. HINT: While the pre-collision brake is canceled, the PCS indicator light on the combination meter turns on. Operative condition Refer to the sensor description under "Outline of Pre-Collision System" (see above). When the distance control ECU determines that a collision is unavoidable, the system performs brake control to reduce the vehicle speed.
6. OPERATIVE CONDITION AND INOPERATIVE CONDITION OF EACH CONTROL (REVIEW) HINT: Each function will operate when all items marked (o) are satisfied. Pre-Collision Seat Belt*1 Pre-Collision Seat Belt*2 Pre-Collision Brake Assist*2 Pre-Collision Brake*2 When power switch is on (IG) o o o o No problem in related components. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568837-S30276286932013072300000) o o o o When front seat belt(s) is/are fastened o o - - Operates when the vehicle speed is 30 km/h (19 mph) or more, regardless of relative speed o - - - Operates when the vehicle speed is 5 km/h (4 mph) or more and relative speed is 30 km/h (19 mph) or more - o - - Operates when the vehicle speed is 15 km/h (10 mph) or more and relative speed is 15 km/h (10 mph) or more - - - o Operates when the vehicle speed is 30 km/h (19 mph) or more and relative speed is 30 km/h (19 mph) or more - - o - When pre-collision brake operation has not been disabled using the pre-collision brake off switch - - - o When the brake pedal is depressed - - o - *1: Operates when sudden braking or skidding is detected. *2: Does not operate in the following situations. 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 cannot detect a possible collision object o: Main basis for operation -: Not main basis for operation
7. 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 driving support ECU may determine that a collision is unavoidable, and activate the pre-collision system. This activation of the system is not abnormal. HINT: The pre-collision system will not activate when approaching safety cones or other plastic objects as they cannot be detected by the pre-collision sensor. 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. Detection performance may deteriorate in the following conditions. Vehicle height changes signifiicantly (front of vehicle inclined either upward or downward) Millimeter wave radar sensor is misaligned (due to reinstallation or collision) 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

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 when sudden braking is detected. The pre-collision seat belts operate when skidding is detected.