ANTI-LOCK BRAKE SYSTEM, Diagnostic DTC:C1271, C1272, C1401, C1402

DTC Code DTC Name
C1271 Low Output Signal of Front Speed Sensor RH (Test Mode DTC)
C1272 Low Output Signal of Front Speed Sensor LH (Test Mode DTC)
C1401 Front Speed Sensor RH Malfunction
C1402 Front Speed Sensor LH Malfunction

DESCRIPTION

The speed sensors detect wheel speed and transmit the signals to the ECU. These signals are used for control of the ABS control system. Each of the skid control rotor has 48 serrations. When the rotors rotate, the magnetic field generated by the permanent magnet in the speed sensor induces an AC voltage.

Since the frequency of this AC voltage changes in direct proportion to the speed of the skid control rotor, the frequency is used by the ECU to detect the speed of each wheel.

A01CHQZE03
DTC No. DTC Detection Condition Trouble Area

C1401

C1402

When any of following conditions detected:


  • When one of the front wheel speeds is 0 km/h (0 mph) or more, and two of the other wheel speeds are 12 km/h (7 mph) or more, one of the wheels has no pulse signal for 30 seconds or more continuously.

  • When the vehicle starts moving, 3 of the wheels are 10 km/h or more, but only one wheel is less than 2 km/h for 0.4 seconds or more continuously.

  • At a vehicle speed of 20 km/h (12 mph) or more, the front two wheels have no pulse signal for 20 seconds or more continuously, occurring in 8 consecutive IG ON←→IG OFF cycles.

  • Harness or connector

  • Front speed sensor RH/LH

  • Front speed sensor installation

  • Front skid control rotor RH/LH

  • Brake actuator assembly

C1271

C1272

 Detected only during Test Mode.

  • Harness or connector

  • Front speed sensor RH/LH

  • Front speed sensor installation

  • Front skid control rotor RH/LH

Tech Tips


  • DTC C1401 and C1271 are for the front speed sensor RH.

  • DTC C1402 and C1272 are for the front speed sensor LH.

WIRING DIAGRAM

A01CJ7OE02

INSPECTION PROCEDURE

Note

Check the speed sensor signal after cleaning or replacement Click here.

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (FRONT SPEED SENSOR)


    1. Warm up the engine.

    2. Turn the ignition switch off.

    3. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    4. Connect the intelligent tester to the DLC3.

    5. Turn the ignition switch to ON.

    6. Turn the intelligent tester on.

    7. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

    8. According to the display on the intelligent tester, read the Data List.

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      FR Wheel Speed FR wheel speed sensor reading / Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

      Vehicle stopped:

      0 km/h

      		 When driving at constant speed: No large fluctuations
      FL Wheel Speed FL wheel speed sensor reading /Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

      Vehicle stopped:

      0 km/h

      		 When driving at constant speed: No large fluctuations

    9. Check that there is no difference between the speed value output from the speed sensor displayed on the intelligent tester and the speed value displayed on the speedometer when driving the vehicle.

      Tech Tips

      Factors that affect the indicated vehicle speed include tire size, tire inflation, 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.

      OK
      The speed value output from the speed sensor displayed on the intelligent tester is the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).

    NG

    CHECK FRONT SPEED SENSOR INSTALLATION Click here

    OK

  2. PERFORM TEST MODE INSPECTION (SIGNAL CHECK)


    1. Perform the sensor check in the Test Mode procedure Click here.

      OK
      All Test Mode DTCs are cleared.

    NG

    CHECK FRONT SPEED SENSOR INSTALLATION Click here

    OK

  3. CHECK SPEED SENSOR AND SKID CONTROL ROTOR SERRATIONS


    1. Turn the ignition switch off.

    2. A01CH4IE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))
      *b RH
      *c LH

      Disconnect the B9 skid control ECU (brake actuator assembly) connector.

    3. Check that a waveform is output by each sensor circuit when the tires are rotated.

      OK
      The same waveform is output from all the 4 wheels and there is no noise or interference in the waveform.

      Tech Tips


      • As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the output voltage becomes greater.


      • When noise is identified in the waveform on the oscilloscope, the erratic signals are generated due to speed sensor rotor's scratches, looseness or foreign matter attached to it.

      Front Speed Sensor RH wheel speed signal (reference)
      Terminal Names B9-6 (FR+) - B9-7 (FR-)
      Tester Ranges 1 V/DIV, 2 ms/DIV
      Conditions wheel speed approximately 30 km/h
      Front Speed Sensor LH wheel speed signal (reference)
      Terminal Names B9-19 (FL+) - B9-18 (FL-)
      Tester Ranges 1 V/DIV, 2 ms/DIV
      Conditions wheel speed approximately 30 km/h

    4. Reconnect the D30 skid control ECU (brake actuator assembly) connector.


    NG

    INSPECT FRONT SPEED SENSOR TIP Click here

    OK

    USE SIMULATION METHOD TO CHECK Click here

  4. CHECK FRONT SPEED SENSOR INSTALLATION


    1. A01CHFPE04
      Text in Illustration
      *1 Front Speed Sensor
      *a No clearance
      *b OK
      *c NG

      Check the front speed sensor installation.

      OK
      There is no clearance between the front speed sensor and the front steering knuckle.

    NG

    INSTALL FRONT SPEED SENSOR CORRECTLY Click here

    OK

  5. INSPECT FRONT SPEED SENSOR


    1. Remove the front speed sensor.

    2. A01CHQ0E01
      Text in Illustration
      *a

      Component without harness connected

      (Front Speed Sensor)
      *b Sensor Housing

      Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      1 - 2 20°C (68°F) 0.9 to 1.3 kΩ
      1 - Sensor housing Always 10 MΩ or higher
      2 - Sensor housing Always 10 MΩ or higher

    3. Reinstall the front speed sensor.


    NG

    REPLACE FRONT SPEED SENSOR Click here

    OK

  6. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - FRONT SPEED SENSOR)


    1. Turn the ignition switch off.

    2. Disconnect the B9 skid control ECU (brake actuator assembly) connector.

    3. Disconnect the F26 and/or F25 front speed sensor connector.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      RH
      Tester Connection Condition Specified Condition
      B9-6 (FR+) - F26-1 (FR+) Always Below 1 Ω
      B9-7 (FR-) - F26-2 (FR-) Always Below 1 Ω
      B9-6 (FR+) or F26-1 (FR+) - Body ground Always 10 kΩ or higher
      B9-7 (FR-) or F26-2 (FR-) - Body ground Always 10 kΩ or higher
      LH
      Tester Connection Condition Specified Condition
      B9-19 (FL+) - F25-1 (FL+) Always Below 1 Ω
      B9-18 (FL-) - F25-2 (FL-) Always Below 1 Ω
      B9-19 (FL+) or F25-1 (FL+) - Body ground Always 10 kΩ or higher
      B9-18 (FL-) or F25-2 (FL-) - Body ground Always 10 kΩ or higher

    5. Reconnect the B9 skid control ECU (brake actuator assembly) connector.

    6. Reconnect the F26 and/or F25 front speed sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK SPEED SENSOR AND SKID CONTROL ROTOR SERRATIONS


    1. Turn the ignition switch off.

    2. A01CH4IE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))
      *b RH
      *c LH

      Disconnect the B9 skid control ECU (brake actuator assembly) connector.

    3. Check that a waveform is output by each sensor circuit when the tires are rotated.

      OK
      The same waveform is output from all the 4 wheels and there is no noise or interference in the waveform.

      Tech Tips


      • As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the output voltage becomes greater.


      • When noise is identified in the waveform on the oscilloscope, the erratic signals are generated due to speed sensor rotor's scratches, looseness or foreign matter attached to it.

      Front Speed Sensor RH wheel speed signal (reference)
      Terminal Names B9-6 (FR+) - B9-7 (FR-)
      Tester Ranges 1 V/DIV, 2 ms/DIV
      Conditions wheel speed approximately 30 km/h
      Front Speed Sensor LH wheel speed signal (reference)
      Terminal Names B9-19 (FL+) - B9-18 (FL-)
      Tester Ranges 1 V/DIV, 2 ms/DIV
      Conditions wheel speed approximately 30 km/h

    4. Reconnect the B9 skid control ECU (brake actuator assembly) connector.


    NG

    INSPECT FRONT SPEED SENSOR TIP Click here

    OK

  8. READ VALUE USING INTELLIGENT TESTER (FRONT SPEED SENSOR)


    1. Warm up the engine.

    2. Turn the ignition switch off.

    3. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    4. Connect the intelligent tester to the DLC3.

    5. Turn the ignition switch to ON.

    6. Turn the intelligent tester on.

    7. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

    8. According to the display on the intelligent tester, read the Data List.

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      FR Wheel Speed FR wheel speed sensor reading / Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

      Vehicle stopped:

      0 km/h

      		 When driving at constant speed: No large fluctuations
      FL Wheel Speed FL wheel speed sensor reading /Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

      Vehicle stopped:

      0 km/h

      		 When driving at constant speed: No large fluctuations

    9. Check that there is no difference between the speed value output from the speed sensor displayed on the intelligent tester and the speed value displayed on the speedometer when driving the vehicle.

      Tech Tips

      Factors that affect the indicated vehicle speed include tire size, tire inflation, 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.

      OK
      The speed value output from the speed sensor displayed on the intelligent tester is the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    OK

    USE SIMULATION METHOD TO CHECK Click here

  9. INSPECT FRONT SPEED SENSOR TIP


    1. Remove the front speed sensor Click here.

    2. Check the front speed sensor tip.

      OK
      No scratches, oil, or foreign matter on the front speed sensor tip.

      Note

      If no damage to the front speed sensor tip is found during this inspection, do not replace the front speed sensor.

    3. Reinstall the front speed sensor.


    NG

    CLEAN OR REPLACE FRONT SPEED SENSOR Click here

    OK

  10. INSPECT FRONT SKID CONTROL ROTOR


    1. Remove the front skid control rotor.

    2. Check the speed sensor rotor.

      OK
      No scratches, oil, or foreign matter on the rotors.

    3. Reinstall the front skid control rotor.


    NG

    CLEAN OR REPLACE FRONT SKID CONTROL ROTOR

    OK

  11. REPLACE FRONT SPEED SENSOR


    1. Replace the front speed sensor Click here.


    NEXT

  12. RECONFIRM DTC


    1. Clear the DTC Click here.

    2. Start the engine.

    3. Drive the vehicle at a speed of 40 km/h (25 mph) or more for at least 60 seconds.

    4. Check if the same DTC is recorded Click here.

      Result
      Result Proceed to
      DTC is not output A
      DTC is output B

    B

    REPLACE FRONT SKID CONTROL ROTOR Click here

    A

    END

  13. REPLACE FRONT SKID CONTROL ROTOR


    1. Replace the front skid control rotor.


    NEXT

  14. RECONFIRM DTC


    1. Clear the DTC Click here.

    2. Start the engine.

    3. Drive the vehicle at a speed of 40 km/h (25 mph) or more for at least 60 seconds.

    4. Check if the same DTC is recorded Click here.

      Result
      Result Proceed to
      DTC is not output A
      DTC is output B

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    A

    END