ANTI-LOCK BRAKE SYSTEM, Diagnostic DTC:C1237, C1275, C1276, C1277, C1278

DTC Code DTC Name
C1237 Speed Sensor Rotor Faulty
C1275 Abnormal Change in Output Signal of Front Speed Sensor RH (Test Mode DTC)
C1276 Abnormal Change in Output Signal of Front Speed Sensor LH (Test Mode DTC)
C1277 Abnormal Change in Output Signal of Rear Speed Sensor RH (Test Mode DTC)
C1278 Abnormal Change in Output Signal of Rear Speed Sensor LH (Test Mode DTC)

DESCRIPTION

The skid control ECU (brake actuator assembly) measures the speed of each wheel by receiving signals from the speed sensor.

These signals are used for recognizing that all four wheels are operating properly.

Therefore, all wheel signals must be equal.

DTCs C1275 to C1278 are cleared when the speed sensor sends a vehicle speed signal or when Test Mode ends. DTCs C1275 to C1278 are output only in Test Mode.

DTC No. DTC Detection Condition Trouble Area
C1237

Any of the following is detected:


  1. Discrepancy among four wheel speed sensor output.

  2. Abnormal pulse signals from 3 or more sensors.

  3. Continuous ABS control is performed for 60 seconds or more.

  • Tire and wheel size

  • Tire deformation

  • Front speed sensor rotor RH/LH (Front axle hub bearing RH/LH)

  • Rear speed sensor rotor RH/LH (Rear axle hub and bearing assembly RH/LH)

  • Front speed sensor RH/LH

  • Rear speed sensor RH/LH

  • Speed sensor circuit

  • Skid control ECU (Brake actuator assembly)

C1275

C1276

 Detected only during Test Mode. Front speed sensor rotor RH/LH (Front axle hub bearing RH/LH)

C1277

C1278

 Detected only during Test Mode. Rear speed sensor rotor RH/LH (Rear axle hub and bearing assembly RH/LH)

Tech Tips


  • DTC C1275 is for the front speed sensor RH.

  • DTC C1276 is for the front speed sensor LH.

  • DTC C1277 is for the rear speed sensor RH.

  • DTC C1278 is for the rear speed sensor LH.

WIRING DIAGRAM

Refer to DTCs C1330, C1331, C1332, C1333, C1464, C1465, C1466 and C1467 Click here for front, and Click here for rear).

INSPECTION PROCEDURE

Tech Tips

When C1330, C1331, C1332, C1333, C1464, C1465, C1466 and/or C1467 is output together with C1237, inspect and repair the trouble areas indicated by C1330, C1331, C1332, C1333, C1464, C1465, C1466 and/or C1467 first Click here for front, and/or Click here for rear).

PROCEDURE


  1. CHECK TIRES


    1. Check the size and condition of all four wheels Click here.

      Tech Tips

      The DTC is output when tire deformation or a difference in tire size is detected.

      OK
      The diameter of all four tires and the tire pressure are the same.

    NG

    REPLACE TIRES SO THAT ALL FOUR TIRES ARE THE SAME SIZE

    OK

  2. READ VALUE USING INTELLIGENT TESTER (SPEED SENSOR)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the intelligent tester on.

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

    5. 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 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
      RR Wheel Speed Rear 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
      RL Wheel Speed Rear 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

    6. Check the speed value output from the speed sensor displayed on the intelligent tester.

      Tech Tips

      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 Click here.

      OK
      The speed value output from the speed sensor displayed on the intelligent tester is similar to the speed indicated on the speedometer.
      Result
      Result Proceed to
      OK A
      NG (for front) B
      NG (for rear) C

    B

    CHECK FRONT SPEED SENSOR AND FRONT SPEED SENSOR ROTOR Click here

    C

    CHECK REAR SPEED SENSOR AND REAR SPEED SENSOR ROTOR Click here

    A

  3. PERFORM TEST MODE INSPECTION (SIGNAL CHECK)


    1. Turn the ignition switch off.

    2. Perform the sensor check using the Test Mode procedure Click here.

      OK
      All Test Mode DTCs are not output.
      Result
      Result Proceed to
      OK A
      NG (for front) B
      NG (for rear) C

    B

    CHECK FRONT SPEED SENSOR AND FRONT SPEED SENSOR ROTOR Click here

    C

    CHECK REAR SPEED SENSOR AND REAR SPEED SENSOR ROTOR Click here

    A

  4. RECONFIRM DTC


    1. Turn the ignition switch off.

    2. Clear the DTCs Click here.

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    6. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is not output. A
      DTC C1237 is output (for front). B
      DTC C1237 is output (for rear). C

    B

    REPLACE FRONT SPEED SENSOR Click here

    C

    REPLACE REAR SPEED SENSOR Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS

  5. CHECK FRONT SPEED SENSOR AND FRONT SPEED SENSOR ROTOR


    1. Remove the front speed sensor and the front speed sensor rotor (front axle hub bearing) Click here for front speed sensor, and Click here for front speed sensor rotor (front axle hub bearing)).

    2. Check the front speed sensor tip and front speed sensor rotor (front axle hub bearing).

      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 Click here.


    NG

    CLEAN OR REPLACE FRONT SPEED SENSOR OR FRONT SPEED SENSOR ROTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - FRONT SPEED SENSOR)


    1. Install the front speed sensor and the front speed sensor rotor (front axle hub bearing).

    2. Disconnect the A46 skid control ECU (brake actuator assembly) connector and the A7 and/or A13 front speed sensor connector.

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

      Standard Resistance
      RH
      Tester Connection Condition Specified Condition
      A46-16 (FR+) - A7-1 (FR+) Always Below 1 Ω
      A46-16 (FR+) - Body ground Always 10 kΩ or higher
      A46-4 (FR-) - A7-2 (FR-) Always Below 1 Ω
      A46-4 (FR-) - Body ground Always 10 kΩ or higher
      LH
      Tester Connection Condition Specified Condition
      A46-19 (FL+) - A13-1 (FL+) Always Below 1 Ω
      A46-19 (FL+) - Body ground Always 10 kΩ or higher
      A46-8 (FL-) - A13-2 (FL-) Always Below 1 Ω
      A46-8 (FL-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. RECONFIRM DTC


    1. Reconnect the skid control ECU (brake actuator assembly) connector and the front speed sensor connector.

    2. Clear the DTCs Click here.

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    6. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is output. A
      DTC C1237 is not output. B

    B

    CHECK FOR INTERMITTENT PROBLEMS

    A

  8. REPLACE FRONT SPEED SENSOR


    1. Turn the ignition switch off.

    2. Replace the front speed sensor Click here.

      Note

      Check the speed sensor signal after replacement Click here.


    NEXT

  9. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Turn the ignition switch off.

    3. Start the engine.

    4. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    5. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is output. A
      DTC C1237 is not output. B

      Tech Tips

      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 Click here.


    B

    END

    A

  10. REPLACE FRONT AXLE HUB BEARING


    1. Turn the ignition switch off.

    2. Replace the front speed sensor rotor (front axle hub bearing) Click here.

      Tech Tips

      If the front speed sensor rotor needs to be replaced, replace the front axle hub bearing.

      Note

      Check the speed sensor signal after replacement Click here.


    NEXT

  11. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Turn the ignition switch off.

    3. Start the engine.

    4. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    5. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is output. A
      DTC C1237 is not output. B

      Tech Tips

      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 Click here.


    B

    END

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

  12. CHECK REAR SPEED SENSOR AND REAR SPEED SENSOR ROTOR


    1. Remove the rear speed sensor and the rear speed sensor rotor (rear axle hub and bearing assembly) Click here for rear speed sensor, and Click here for rear speed sensor rotor (rear axle hub and bearing assembly).

    2. Check the rear 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 Click here.


    NG

    CLEAN OR REPLACE REAR SPEED SENSOR OR REAR SPEED SENSOR ROTOR

    OK

  13. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - REAR SPEED SENSOR)


    1. Install the rear speed sensor and the rear speed sensor rotor (rear axle hub and bearing assembly).

    2. Disconnect the A46 skid control ECU (brake actuator assembly) connector and the H3 and/or H4 rear speed sensor connector.

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

      Standard Resistance
      RH
      Tester Connection Condition Specified Condition
      A46-17 (RR+) - H3-1 (RR+) Always Below 1 Ω
      A46-17 (RR+) - Body ground Always 10 kΩ or higher
      A46-29 (RR-) - H3-2 (RR-) Always Below 1 Ω
      A46-29 (RR-) - Body ground Always 10 kΩ or higher
      LH
      Tester Connection Condition Specified Condition
      A46-31 (RL+) - H4-1 (RL+) Always Below 1 Ω
      A46-31 (RL+) - Body ground Always 10 kΩ or higher
      A46-18 (RL-) - H4-2 (RL-) Always Below 1 Ω
      A46-18 (RL-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  14. RECONFIRM DTC


    1. Reconnect the skid control ECU (brake actuator assembly) connector and the rear speed sensor connector.

    2. Clear the DTCs Click here.

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    6. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is output. A
      DTC C1237 is not output. B

    B

    CHECK FOR INTERMITTENT PROBLEMS

    A

  15. REPLACE REAR SPEED SENSOR


    1. Turn the ignition switch off.

    2. Replace the rear speed sensor Click here.

      Note

      Check the speed sensor signal after replacement Click here.


    NEXT

  16. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Turn the ignition switch off.

    3. Start the engine.

    4. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    5. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is output. A
      DTC C1237 is not output. B

      Tech Tips

      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 Click here.


    B

    END

    A

  17. REPLACE REAR AXLE HUB AND BEARING ASSEMBLY


    1. Turn the ignition switch off.

    2. Replace the rear speed sensor rotor (rear axle hub and bearing assembly) Click here.

      Tech Tips

      If the rear speed sensor rotor needs to be replaced, replace the rear axle hub and bearing assembly.

      Note

      Check the speed sensor signal after replacement Click here.


    NEXT

  18. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Turn the ignition switch off.

    3. Start the engine.

    4. Drive the vehicle at a speed of 45 km/h (28 mph) or more for at least 120 seconds.

    5. Check if the same DTC is output Click here.

      Result
      Result Proceed to
      DTC C1237 is output. A
      DTC C1237 is not output. B

      Tech Tips

      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 Click here.


    B

    END

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here