Vehicle Stability Control System (Diagnostic Codes & Circuit Tests): Overview Lexus IS III

DESCRIPTION

This circuit is used to send TRAC and VSC operation information from the skid control ECU (brake actuator assembly) to the ECM, and engine control information from the ECM to the skid control ECU (brake actuator assembly) via CAN communication.

The skid control ECU (brake actuator assembly) receives signals from the yaw rate and acceleration sensor via CAN communication.

HINT

If there is a malfunction in the bus lines between the yaw rate and acceleration sensor and the CAN communication system, DTCs U0123 (Lost Communication with Yaw Rate Sensor Module) and U0124 (Lost Communication with Lateral Acceleration Sensor Module) are output. When DTCs U0123 and/or U0124 are output together with C1210 and/or C1336, inspect and repair the trouble areas indicated by U0123 and/or U0124 first.

These DTCs are also output when the calibration has not been completed.

These solenoids turn on when signals are received from the skid control ECU (brake actuator assembly) and they control the pressure acting on the wheel cylinders to control the braking force.

The skid control ECU (brake actuator assembly) receives signals from the yaw rate and acceleration sensor via CAN communication.

HINT

If there is a malfunction in the bus lines between the yaw rate and acceleration sensor and the CAN communication system, DTCs U0123 (Lost Communication with Yaw Rate Sensor Module) and U0124 (Lost Communication with Lateral Acceleration Sensor Module) are output. When DTCs U0123 and/or U0124 are output together with C1232, C1243 and/or C1245, inspect and repair the trouble areas indicated by U0123 and/or U0124 first.

DTCs may be stored if either of the following occurs

1. Yaw rate and acceleration sensor installation abnormality.
2. Yaw rate and acceleration sensor signal malfunction.

DTC C1279 can be cleared when the yaw rate and acceleration sensor sends a yaw rate and/or acceleration signal or when Test Mode ends. DTC C1279 is output only in Test Mode.

HINT

for C1243 and C1245: Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed.

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

If a malfunction is detected in the power supply circuit, the skid control ECU (brake actuator assembly) stores this DTC and the fail-safe function prohibits ABS operation.

This DTC is stored when the IG1 terminal voltage deviates due to a malfunction in the power supply or charging circuit such as the battery or alternator circuit, etc.

The DTC is cleared when the IG1 terminal voltage returns to normal.

Scheme 43

Each speed sensor detects wheel speed and sends signals to the skid control ECU (brake actuator assembly). These signals are used by the ABS.

The speed sensor rotors have rows of alternating N and S magnetic poles.

Hall IC type speed sensors use the frequency of output pulses to detect the vehicle speed. Because the sensor outputs digital pulses, it can detect the vehicle speed even when the vehicle is nearly stationary.

DTCs C1271, C1272, C1275 and C1276 are cleared when the speed sensor sends a vehicle speed signal or when Test Mode ends. DTCs C1271, C1272, C1275 and C1276 are output only in Test Mode.

Scheme 44

HINT

Check the connection status between the sensor connector and the vehicle wire harness.

HINT

for C1413 and C1414: Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed.

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

HINT

1. DTC C1413 is for the front speed sensor RH.
2. DTC C1414 is for the front speed sensor LH.

Scheme 45

Each speed sensor detects the wheel speed and sends signals to the skid control ECU (brake actuator assembly). These signals are used by the ABS.

The speed sensor rotors have rows of alternating N and S magnetic poles. Hall IC type speed sensors use the frequency of output pulses to detect the vehicle speed. Because the sensor outputs digital pulses, it can detect the vehicle speed even when the vehicle is nearly stationary.

DTCs C1273, C1274, C1277 and C1278 are cleared when the speed sensor sends a vehicle speed signal or when Test Mode ends. DTCs C1273, C1274, C1277 and C1278 are output only in Test Mode.

Scheme 46

HINT

Check the connection status between the sensor connector and the vehicle wire harness.

HINT

for C1415 and C1416: Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed.

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

HINT

1. DTC C1415 is for the rear speed sensor RH.
2. DTC C1416 is for the rear speed sensor LH.

Scheme 47

The master cylinder pressure sensor is connected to the skid control ECU in the brake actuator assembly.

DTC C1281 will be cleared when the master cylinder pressure sensor sends a master cylinder pressure signal or when Test Mode ends. DTC C1281 is output only in Test Mode.

Scheme 48

HINT

for C1422: Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed.

1. Turn the engine switch on (IG).
2. Keep the vehicle stationary for 5 seconds or more and depress the brake pedal lightly 2 or 3 times.
3. Drive the vehicle at the vehicle speed of 50 km/h (31 mph) and depress and hold the brake pedal firmly for approximately 3 seconds.
4. Repeat the above operation 3 times or more and check that the ABS warning light goes off.
5. Clear the DTCs.

The skid control ECU (brake actuator assembly) communicates with the front steering control ECU via CAN communication.

If a malfunction in the VGRS system is detected, cooperative control of the steering is prohibited by the fail-safe function.

The skid control ECU (brake actuator assembly) acquires steering angle sensor zero point every time the engine switch is turned on (IG) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The skid control ECU (brake actuator assembly) also stores the previous zero point.

If front wheel alignment or the steering wheel position is adjusted without disconnecting the negative battery terminal, or if yaw rate and acceleration sensor zero point is not acquired after the adjustments have been completed, the skid control ECU (brake actuator assembly) detects the difference between the previous zero point and newly acquired zero point and stores this DTC to indicate a poor adjustment.

The warning operation for the steering angle sensor zero point malfunction will be canceled by turning the engine switch off.

The ABS motor relay supplies power to the pump motor. While the ABS is activated, the ECU turns the ABS motor relay on and operates the pump motor.

If the voltage supplied to the ABS motor relay (+BM) is below the DTC detection threshold due to low voltage from the battery or alternator, these DTCs may be stored.

HINT

for C146C: Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed.

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

Scheme 49

This DTC is stored when the skid control ECU (brake actuator assembly) receives a sensor supply voltage malfunction signal from the yaw rate and acceleration sensor.

Scheme 50

Refer to DTCs C1413 and C1414.

Refer to DESCRIPTION

HINT

Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

HINT

1. DTC C1401 is for the front speed sensor RH.
2. DTC C1402 is for the front speed sensor LH.

Scheme 51

1. CHECK FRONT SPEED SENSOR INSTALLATION Check the speed sensor installation. OK There is no clearance between the sensor and the front steering knuckle. The installation bolt is tightened properly. Torque 8.5 N*m (87 kgf*cm, 75 in.*lbf) *1 Front Speed Sensor *A for 2WD *B for AWD *a Correct *b Incorrect *c 8.5 Nm *d No clearance Result Result Proceed to OK (for AWD) A OK (for 2WD) B NG C Result: 2 B See step 3 Result: 3 C INSTALL FRONT SPEED SENSOR CORRECTLY for 2WD: Refer to «INSTALLATION [04/2013 - ]»(ref-665739-S39563371812014102400000) for AWD: Refer to «INSTALLATION [04/2013 - ]»(ref-665739-S36988163242014102400000) Result: 1 A See step 2
2. CHECK FRONT SPEED SENSOR AND SENSOR ROTOR Remove the front speed sensor and the component with the sensor rotor. for speed sensor: Refer to «REMOVAL [04/2013 - ]»(ref-665739-S02228617722014102400000) for sensor rotor: Refer to «REMOVAL [04/2013 - ]»(ref-665775-S42212850262014102400000) Check the speed sensor tip and speed sensor rotor. OK No scratches, oil, or foreign matter on the sensor tip and rotor. NOTE: If no damage to the speed sensor tip is found during this inspection, do not replace the speed sensor. If there are any ferrous metal filings stuck to the rotor, this will result in a malfunction, so confirm that the rotor is not contaminated with foreign matter before replacing the sensor. Check the speed sensor signal after cleaning or replacement. Refer to «TEST MODE PROCEDURE [04/2013 - ]»(ref-665532-S38912383922014102400000) Result Proceed to OK NG Result: 2 NG CLEAN OR REPLACE FRONT SPEED SENSOR OR COMPONENT WITH SENSOR ROTOR Result: 1 OK See step 3
3. READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR) Install the front speed sensor and the component with the sensor rotor. Connect the Techstream to the DLC3. Start the engine. Select the Data List using the Techstream. Refer to «DATA LIST / ACTIVE TEST [04/2013 - ]»(ref-665532-S12748400992014102400000) Chassis > ABS/VSC/TRAC > Data List Tester Display Measurement Item Range Normal Condition Diagnostic Note FR Wheel Speed Front wheel speed sensor RH reading Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph) Vehicle stopped: 0 km/h (0 mph) When driving at constant speed: No large fluctuations FL Wheel Speed Front wheel speed sensor LH reading Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph) Vehicle stopped: 0 km/h (0 mph) When driving at constant speed: No large fluctuations Chassis > ABS/VSC/TRAC > Data List Tester Display FR Wheel Speed FL Wheel Speed Check the speed value output from the speed sensor displayed on the Techstream. HINT: Factors that affect the indicated vehicle speed include tire size, tire pressure, and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, see the reference chart. Refer to «ON-VEHICLE INSPECTION [04/2013 - ]»(ref-665736-S02618142942014102400000) OK The speed value output from the speed sensor displayed on the Techstream is similar to the speed indicated on the speedometer. Result Result Proceed to OK (for AWD) A OK (for 2WD) B NG C HINT: for 2WD: The front speed sensor rotor and front speed sensor are incorporated into the front axle hub sub-assembly. If the front speed sensor rotor needs to be replaced, replace the front axle hub sub-assembly with front speed sensor. If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts. Result: 2 B REPLACE FRONT AXLE HUB SUB-ASSEMBLY. Refer to «REMOVAL [04/2013 - ]»(ref-665775-S42212850262014102400000) Result: 3 C USE SIMULATION METHOD TO CHECK. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING [04/2013 - ]»(ref-665529-S21853141262014102400000) Result: 1 A See step 4
4. REPLACE FRONT SPEED SENSOR Turn the engine switch off. Replace the front speed sensor. Refer to «REMOVAL [04/2013 - ]»(ref-665739-S02228617722014102400000) NOTE: Check the speed sensor signal after replacement. Refer to «TEST MODE PROCEDURE [04/2013 - ]»(ref-665532-S38912383922014102400000) Result Proceed to NEXT Result: 1 NEXT See step 5
5. RECONFIRM DTC Clear the DTCs. Refer to «DTC CHECK / CLEAR [04/2013 - ]»(ref-665532-S37150082782014102400000) Chassis > ABS/VSC/TRAC > Clear DTCs Turn the engine switch off. Start the engine. Perform a road test. Check if the same DTC is output. Refer to «DTC CHECK / CLEAR [04/2013 - ]»(ref-665532-S37150082782014102400000) Chassis > ABS/VSC/TRAC > Trouble Codes Result Result Proceed to DTCs C1401 and C1402 are not output. A DTCs C1401 and/or C1402 are output. B NOTE: Check the speed sensor signal after replacement. Refer to «TEST MODE PROCEDURE [04/2013 - ]»(ref-665532-S38912383922014102400000) HINT: for AWD: The front speed sensor rotor is incorporated into the front axle hub sub-assembly. If the front speed sensor rotor needs to be replaced, replace the front axle hub sub-assembly. If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts. Refer to «PROBLEM SYMPTOMS TABLE [04/2013 - ]»(ref-665532-S20301770492014102400000) Result: 1 A END Result: 2 B REPLACE FRONT AXLE HUB SUB-ASSEMBLY. Refer to «REMOVAL [04/2013 - ]»(ref-665775-S42212850262014102400000)

Refer to DTCs C1415 and C1416.

Refer to DESCRIPTION

HINT

Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

HINT

1. DTC C1403 is for the rear speed sensor RH.
2. DTC C1404 is for the rear speed sensor LH.

Refer to DTCs C1413 and C1414.

Refer to DTC C1271: Low Output Signal of Front Speed Sensor RH (Test Mode DTC); DTC C1272: Low Output Signal of Front Speed Sensor LH (Test Mode DTC); DTC C1275: Abnormal Change in Output Signal of Front Speed Sensor RH (Test Mode DTC); DTC C1276: Abnormal Change in Output Signal of Front Speed Sensor LH (Test Mode DTC); DTC C1413: Front Speed Sensor RH Output Malfunction; DTC C1414: Front Speed Sensor LH Output Malfunction [04/2013 - ]

HINT

1. DTC C1405 is for the front speed sensor RH.
2. DTC C1406 is for the front speed sensor LH.

Refer to DTCs C1415 and C1416.

Refer to DTC C1273: Low Output Signal of Rear Speed Sensor RH (Test Mode DTC); DTC C1274: Low Output Signal of Rear Speed Sensor LH (Test Mode DTC); DTC C1277: Abnormal Change in Output Signal of Rear Speed Sensor RH (Test Mode DTC); DTC C1278: Abnormal Change in Output Signal of Rear Speed Sensor LH (Test Mode DTC); DTC C1415: Rear Speed Sensor RH Output Malfunction; DTC C1416: Rear Speed Sensor LH Output Malfunction [04/2013 - ]

HINT

1. DTC C1407 is for the rear speed sensor RH.
2. DTC C1408 is for the rear speed sensor LH.

The speed sensor rotors have rows of alternating N and S magnetic poles.

Hall IC type speed sensors use the frequency of output pulses to detect the vehicle speed. Because the sensor outputs digital pulses, it can detect the vehicle speed even when the vehicle is nearly stationary.

HINT

1. DTC C1409 is for the front speed sensor RH.
2. DTC C1410 is for the front speed sensor LH.

The speed sensor rotors have rows of alternating N and S magnetic poles. Hall IC type speed sensors use the frequency of output pulses to detect the vehicle speed. Because the sensor outputs digital pulses, it can detect the vehicle speed even when the vehicle is nearly stationary.

HINT

1. DTC C1411 for the rear speed sensor RH.
2. DTC C1412 for the rear speed sensor LH.

If a malfunction is detected in the power supply circuit, the skid control ECU (brake actuator assembly) stores this DTC and the fail-safe function prohibits ABS operation.

This DTC is stored when the IG1 terminal voltage deviates due to a malfunction in the power supply or charging circuit such as the battery or alternator circuit, etc.

The DTC is cleared when the IG1 terminal voltage returns to normal.

These DTCs are stored when the skid control ECU (brake actuator assembly) receives an internal malfunction signal from the yaw rate and acceleration sensor.

The skid control ECU (brake actuator assembly) receives signals from the yaw rate and acceleration sensor via CAN communication.

HINT

for C1423 and C1424: Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed

1. Turn the engine switch on (IG).
2. Keep the vehicle stationary for 5 seconds or more and depress the brake pedal lightly 2 or 3 times.
3. Drive the vehicle at the vehicle speed of 50 km/h (31 mph) and depress and hold the brake pedal firmly for approximately 3 seconds.
4. Repeat the above operation 3 times or more and check that the ABS warning light goes off.
5. Clear the DTCs.

The skid control ECU (brake actuator assembly) receives stop light switch signals and uses them to determine whether or not the brakes are applied.

The skid control ECU (brake actuator assembly) has a detection circuit that it uses to detect an open in the stop light input line.

If the skid control ECU (brake actuator assembly) detects an open in this circuit, it will store this DTC.

Scheme 52

The skid control ECU (brake actuator assembly) receives stop light switch signals and uses them to determine whether or not the brakes are applied.

The skid control ECU (brake actuator assembly) has a detection circuit that it uses to detect an open in the stop light input line.

If the skid control ECU (brake actuator assembly) detects an open in this circuit, it will store this DTC.

HINT

Even after the trouble areas are repaired, the ABS warning light will not go off unless the following operations are performed

1. Drive the vehicle at 30 km/h (19 mph) for 30 seconds or more and check that the ABS warning light goes off.
2. Clear the DTCs.

The brake pedal load sensing switch (brake pedal support assembly) turns on when the brake pedal is depressed with a force exceeding a predetermined level.

The skid control ECU (brake actuator assembly) uses this circuit to detect if the brake pedal is depressed or not.

Scheme 53

The brake pedal load sensing switch (brake pedal support assembly) turns on when the brake pedal is depressed with a force exceeding a predetermined level.

The skid control ECU (brake actuator assembly) uses this circuit to detect if the brake pedal is depressed or not.

This DTC is stored when the skid control ECU (brake actuator assembly) receives a power supply open signal from the steering angle sensor.

This DTC is stored when the skid control ECU (brake actuator assembly) receives an internal malfunction signal from the steering angle sensor.

The skid control ECU (brake actuator assembly) receives signals from the steering angle sensor via CAN communication.

HINT

If there is a malfunction in the bus lines between the steering angle sensor and the CAN communication system, DTCs U0073 (Control Module Communication Bus OFF), U0124 (Lost Communication with Lateral Acceleration Sensor Module) and/or U0126 (Lost Communication with Steering Angle Sensor Module) are output. When U0073, U0124 and/or U0126 are output together with C1434, inspect and repair the trouble areas indicated by U0073, U0124 and/or U0126 first.

DTCs may be stored if one of the following occurs

1. Steering angle sensor zero point value malfunction.
2. Steering angle sensor signal malfunction.
3. Steering angle sensor installation abnormality.

This DTC is stored when the skid control ECU (brake actuator assembly) detects improper installation of the yaw rate and acceleration sensor or an abnormality in the difference between the yaw rate sensor value and the control value estimated based on the acceleration sensor, steering angle sensor and speed sensor signals.

The skid control ECU (brake actuator assembly) receives signals from the ECM via CAN communication.

The skid control ECU (brake actuator assembly) acquires the steering angle sensor zero point every time the engine switch is turned on (IG) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The ECU also stores previous zero points.

If the skid control ECU (brake actuator assembly) determines that the vehicle is being driven at a steep bank angle, the skid control ECU (brake actuator assembly) stores DTC C1440 while VSC operation is temporarily disabled.

This is not a malfunction if the system and sensor circuits are normal and normal VSC operation resumes.

The skid control ECU (brake actuator assembly) receives signals from the yaw rate and acceleration sensor via CAN communication.

The skid control ECU (brake actuator assembly) acquires the steering angle sensor zero point every time the engine switch is turned on (IG) and the vehicle is driven at 35 km/h (22 mph) or more for approximately 5 seconds. The ECU also stores previous zero points.

The ABS solenoid relay supplies power to the ABS solenoid and TRAC solenoid.

The solenoid relay is turned on 1.5 seconds after the engine switch is turned on (IG), and is turned off if an open or short in the solenoid is detected by self diagnosis performed when the vehicle starts running.

The ABS solenoid relay is housed in the skid control ECU in the brake actuator assembly.

Scheme 54

The skid control ECU (brake actuator assembly) receives signals from the ECM, steering angle sensor, yaw rate and acceleration sensor and front steering control ECU via CAN communication.

Scheme 55

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

If any of the following is detected, the ABS warning light remains on

1. The skid control ECU (brake actuator assembly) connector is disconnected from the skid control ECU (brake actuator assembly).
2. There is a malfunction in the skid control ECU (brake actuator assembly) internal circuit.
3. There is an open in the harness between the combination meter assembly and the skid control ECU (brake actuator assembly).
4. The ABS is defective.

HINT

In some cases, the cannot be used when the skid control ECU (brake actuator assembly) is abnormal.

Scheme 56

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

If any of the following is detected, the brake warning light remains on

1. The skid control ECU (brake actuator assembly) connector is disconnected from the skid control ECU (brake actuator assembly).
2. The brake fluid level is insufficient.
3. The parking brake is applied.
4. EBD operation is not possible.
5. The brake booster assembly is judged to be defective.

Scheme 57

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

The slip indicator light blinks during VSC and/or TRAC operation.

If a malfunction is detected, the slip indicator light comes on to warn the driver.

Refer to DIAGNOSIS SYSTEM [04/2013 - ]

Scheme 58

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

Connecting terminals TC and CG of the DLC3 causes the ECU to display DTCs by blinking the ABS warning and slip indicator lights.

Scheme 59

Connecting terminals TS and CG of the DLC3 causes the ECU to display Test Mode DTCs by blinking the ABS warning and slip indicator lights.

In Test Mode (signal check), a malfunction in a speed sensor that cannot be detected when the vehicle is stopped can be detected while driving.

Sensor check mode can be entered by connecting terminals TS and CG of the DLC3 and turning the engine switch from off to on (IG).

Scheme 60

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

Pressing the VSC OFF switch (combination switch assembly) turns off TRAC operation, and pressing and holding this switch turns off TRAC and VSC operation. If TRAC and VSC operations are turned off, the TRAC OFF message will be displayed on the multi-information display and the VSC OFF indicator light will come on.

Scheme 61

See also:
• DIAGNOSIS SYSTEM [04/2013 - ]
• ADJUSTMENT [04/2013 - ]
• REMOVAL [04/2013 - ]
• REMOVAL [04/2013 - ]