Pre-Collision (Diagnostic Codes & Circuit Tests): Overview Lexus CT I

DESCRIPTION

The seat belt control ECU receives information from the driving support ECU using CAN communication and tightens the seat belt by operating the motor in the front seat outer belt assembly RH.

Scheme 178

The seat belt control ECU receives information from the driving support ECU using CAN communication and tightens the seat belt by operating the motor in the front seat outer belt assembly RH.

The seat belt control ECU receives information from the driving support ECU using CAN communication and tightens the seat belt by operating the motor in the front seat outer belt assembly RH.

The seat belt control ECU receives information from the driving support ECU using CAN communication and tightens the seat belt by operating the motor in the front seat outer belt assembly LH.

Scheme 179

The seat belt control ECU receives information from the driving support ECU using CAN communication and tightens the seat belt by operating the motor in the front seat outer belt assembly LH.

The seat belt control ECU receives information from the driving support ECU using CAN communication and tightens the seat belt by operating the motor in the front seat outer belt assembly LH.

The DTCs above are stored during seat belt control ECU self-diagnosis.

HINT

1. When DTC B2015 or B2016 is detected, DTCs B2026 and B2027 will not be detected.
2. When DTC B2020 or B2021 is detected, DTCs B2031 and B2032 will not be detected.

If the seat belt control ECU judges that there is a malfunction in its internal circuit as a result of self-diagnosis, or if the power source voltage (+B) is not input to the seat belt control ECU, this DTC will be stored.

This DTC is stored when a malfunction in the electronically controlled brake system is detected. This circuit consists of the brake booster with master cylinder (skid control ECU) and seat belt control ECU. Signals are sent from the brake booster with master cylinder (skid control ECU) using CAN communication.

The seat belt control ECU is connected to the main body ECU using CAN communication.

The seat belt control ECU receives vehicle model information from the main body ECU and determines whether the seat belt buckle switch information from the center airbag sensor assembly is for the driver seat or the passenger seat.

DTC B2064 is stored when the CAN communication frame with the main body ECU is normal and communication is available, but the steering wheel position information is not set or varies.

These DTCs are stored when a malfunction is detected in the driver side seat buckle switch circuit or passenger side seat buckle switch circuit.

Scheme 180

This DTC is stored when CAN communication between the driving support ECU and brake booster with master cylinder (skid control ECU) is interrupted.

This circuit consists of the driving support ECU, brake booster with master cylinder (skid control ECU) and seat belt control ECU. DTC B2085 is stored when the seat belt control ECU detects an interruption in CAN communication between the driving support ECU and brake booster with master cylinder (skid control ECU).

The seat belt control ECU receives collision information from the driving support ECU and brake booster with master cylinder (skid control ECU) via CAN communication, and tightens the seat belts by operating the motor inside each front seat outer belt assemblies.

When the driving support ECU detects a malfunction in the dynamic radar cruise control system and pre-collision system, the malfunction information is sent to the seat belt control ECU, which outputs this DTC.

When DTC B2090 is stored, other DTCs are also stored by the driving support ECU (dynamic radar cruise control system and pre-collision system).

The driving support ECU uses the millimeter wave radar sensor to detect obstacles in front of the vehicle.

Based on this information, the driving support ECU calculates the risk of a collision and operates the pre-collision system when it determines that the risk is high.

When a new driving support ECU is installed, it receives vehicle specification information (destination, steering wheel position, 2WD or AWD information, etc.) from the main body ECU and power management control ECU and memorizes the information.

DTC C1A02 is stored when the driving support ECU receives the vehicle specification information from the main body ECU but cannot record it.

The driving support ECU uses the millimeter wave radar sensor to detect obstacles in front of the vehicle.

Based on this information, the driving support ECU sends pre-collision control operation signals.

When the millimeter wave radar sensor is replaced with a new one, it acquires the country specification information from the driving support ECU. Also, when the driving support ECU is replaced with a new one, it receives country specification information from the main body ECU. When country specification information in the sensor, ECU and/or main body ECU do not match, DTC C1A0A is stored.

The driving support ECU uses the millimeter wave radar sensor to detect obstacles in front of the vehicle.

Based on this information, the driving support ECU sends pre-collision control operation signals.

When the driving support ECU receives information that there is a malfunction in the millimeter wave radar sensor, DTC C1A10 is stored.

The driving support ECU uses the millimeter wave radar sensor to detect obstacles in front of the vehicle.

Based on this information, the driving support ECU sends pre-collision control operation signals.

When the vehicle is determined to be driving in a straight line or on a slow curve based on signals from the yaw rate sensor etc., the millimeter wave radar sensor performs a self diagnosis to check if the sensor beam axis is deviated from the vehicle movement direction. When the millimeter wave radar sensor beam axis is deviated, the driving support ECU detects this, and stores DTC C1A11.

After installing a new millimeter wave radar sensor, if the sensor beam axis adjustment is not performed, DTC C1A14 is stored.

When the driving support ECU receives a hybrid control system or engine control system malfunctioning signal from the power management control ECU via the CAN communication system, DTC C1A40 is stored.

When DTC C1A40 is stored, hybrid control system or engine control system DTCs will also be stored.

The brake booster with master cylinder (skid control ECU) receives brake control request signals from the power management control ECU and driving support ECU.

When the request signals received from the power management control ECU and driving support ECU are not consistent, the brake booster with master cylinder (skid control ECU) determines that a malfunction has occurred and sends a malfunction signal to the driving support ECU.

If the driving support ECU receives a malfunction signal, DTC C1A41 is stored.

The brake booster with master cylinder (skid control ECU) receives vehicle stability signals from the yaw rate sensor and sends the signals to the driving support ECU and power management control ECU. If the brake booster with master cylinder (skid control ECU) detects that the yaw rate sensor is malfunctioning, the brake booster with master cylinder (skid control ECU) sends a malfunction signal to the driving support ECU, and the driving support ECU stores DTC C1A46. Also, when DTC C1A46 is stored, the brake booster with master cylinder (skid control ECU) stores DTC C1234 at the same time.

The brake booster with master cylinder (skid control ECU) receives steering rotation angle information from the steering angle sensor, and sends the information to the driving support ECU via CAN communication.

If the brake booster with master cylinder (skid control ECU) detects a malfunction of the steering angle sensor, it sends a malfunction signal to the driving support ECU and stores a DTC.

Based on pre-collision control, the driving support ECU communicates to the driver to be careful. The driving support ECU performs this by sending a sounding signal to the brake booster with master cylinder (skid control ECU) to sound the skid control buzzer.

When the brake booster with master cylinder (skid control ECU) detects a malfunction in the VSC warning buzzer circuit, a malfunction signal is sent to the driving support ECU, and this DTC is stored. Although the brake booster with master cylinder (skid control ECU) sends a malfunction signal to the driving support ECU, the vehicle stability control system does not store a relevant malfunction detection DTC.

The stop light switch assembly sends a brake pedal operation signal to the driving support ECU. Based on the signal, the driving support ECU cancels cruise control.

1. The driving support ECU uses the millimeter wave radar sensor to detect obstacles in front of the vehicle. Based on this information, the driving support ECU sends pre-collision control operation signals. These DTCs are stored when a communication malfunction occurs between the sensors and ECUs that detect collisions, or between ECUs that perform the pre-collision control.

1. The driving support ECU sends vehicle speed and vehicle condition information to the millimeter wave radar sensor. The millimeter wave radar sensor then sends information on the presence, distance, and relative speed of objects ahead to the driving support ECU. The driving support ECU sends this information to the ECM and performs pre-collision system (DTC U1104). DTC No. DTC Detection Condition Trouble Area U0122 When the power switch is on (IG), a communication error between the brake booster with master cylinder (skid control ECU) and the driving support ECU is detected for approx. 3 seconds. When the power switch is on (IG), a communication error between the skid control ECU assembly and the seat belt control ECU is detected for approx. 3 seconds. Brake booster with master cylinder (skid control ECU) CAN communication system Driving support ECU Wire harness or connector U0123 When the power switch is on (IG), a communication error between the yaw rate sensor and the driving support ECU is detected for approx. 1 second. Yaw rate sensor CAN communication system Driving support ECU U0126 When the power switch is on (IG), a communication error between the steering angle sensor and the driving support ECU is detected for approx. 1 second. Steering angle sensor CAN communication system Driving support ECU U0140 When the power switch is on (IG), communication stop between the main body ECU and seat belt control ECU continues for 6 seconds or more. Main body ECU CAN communication system Seat belt control ECU Wire harness or connector U0151 When the power switch is on (IG), communication stop between the center airbag sensor and seat belt control ECU continues for 6 seconds or more. Center airbag sensor CAN communication system Seat belt control ECU Wire harness or connector U0293 When the power switch is on (IG), a communication error between the power management control ECU and brake booster with master cylinder (skid control ECU) is detected for approx. 1 second. When the power switch is on (IG), a communication error between the power management control ECU and driving support ECU is detected for approx. 1 second. Power management control ECU Brake booster with master cylinder (skid control ECU) CAN communication system Driving support ECU U1100 When the power switch is on (IG), a communication error between the seat belt control ECU and the driving support ECU is detected for approx. 1 second. Seat belt control ECU CAN communication system Driving support ECU U1104 When the power switch is on (IG), a communication error between the driving support ECU and the millimeter wave radar sensor is detected for approx. 1 second. When the power switch is on (IG), a communication error between the driving support ECU and the power management control ECU is detected for approx. 1 second. When the power switch is on (IG), a communication error between the driving support ECU and seat belt control ECU is detected for approx. 1 second. Communication circuit Millimeter wave radar sensor Driving support ECU CAN communication system Wire harness or connector

Scheme 181

The driving support ECU sends information on steering angle and steering direction to the millimeter wave radar sensor. The millimeter wave radar sensor then sends information on the presence, distance, and relative speed of objects ahead to the driving support ECU. The driving support ECU sends this information to the power management control ECU and performs cruise control.

Scheme 182

The driving support ECU receives a pre-collision brake on/off signal from the pre-collision brake off switch assembly.

Scheme 183

Scheme 184

1. READ VALUE USING TECHSTREAM (PRE-COLLISION BRAKE OFF SWITCH ASSEMBLY) Use the Data List to check if the pre-collision brake off switch assembly is functioning properly. PRE-COLLISION 2 Tester Display Measurement Item/Range Normal Condition Diagnostic Note Pre-Collision Brake OFF Switch Pre-collision brake off switch signal/ON or OFF ON: Pre-collision brake off switch on OFF: Pre-collision brake off switch off - OK On screen, each item changes between ON and OFF according to above chart. NG --> See step 2 OK --> See step 5
2. INSPECT PRE-COLLISION BRAKE OFF SWITCH ASSEMBLY Remove the pre-collision brake off switch assembly. Refer to «REMOVAL»(/lexus/ct/i-2010-2014/remont/airbag/#pre-collision-service-information) . Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Switch Condition Specified Condition 1 - 2 Pressed Below 1 ohms Not pressed 10 kohms or higher TEXT IN ILLUSTRATION *a Component without harness connected (Pre-collision Brake Off Switch Assembly) Reinstall the pre-collision brake off switch assembly. Refer to «INSTALLATION»(/lexus/ct/i-2010-2014/remont/airbag/#pre-collision-service-information) . NG --> See step 6 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (PRE-COLLISION BRAKE OFF SWITCH - DRIVING SUPPORT ECU, BODY GROUND) Disconnect the pre-collision brake off switch assembly connector. Disconnect the driving support ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H33-1 - H5-5 (PBSW) Always Below 1 ohms H33-1 - Body ground Always 10 kohms or higher H33-2 - Body ground Always Below 1 ohms Reconnect the driving support ECU connector. Reconnect the pre-collision brake off switch assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (PRE-COLLISION BRAKE OFF SWITCH - DRIVING SUPPORT ECU) OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (PRE-COLLISION BRAKE OFF SWITCH ASSEMBLY - BODY GROUND) Disconnect the pre-collision brake off switch assembly connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition H33-2 - Body ground Always Below 1 ohms Reconnect the pre-collision brake off switch assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (PRE-COLLISION BRAKE OFF SWITCH ASSEMBLY - BODY GROUND) OK --> See step 7
5. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-568837-S30276286932013072300000)
6. REPLACE PRE-COLLISION BRAKE OFF SWITCH ASSEMBLY. Refer to «REMOVAL»(/lexus/ct/i-2010-2014/remont/airbag/#pre-collision-service-information)
7. REPLACE DRIVING SUPPORT ECU. Refer to «REMOVAL»(/lexus/ct/i-2010-2014/remont/cruise-control-systems/#cruise-control-system-service-information)

This circuit supplies power to the seat belt control ECU.

Scheme 185

See also:
• REMOVAL
• REMOVAL
• REMOVAL