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

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

DESCRIPTION

The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU. These signals are used for brake control.

The speed sensor rotors have rows of alternating N and S magnetic poles and their magnetic fields change when the rotors turn.

Each speed sensor detects that magnetic change and sends a pulse signal to the skid control ECU.

Tech Tips

When the connectors between the speed sensor and skid control ECU are connected, the following waveform is output.

B001HQRE12
DTC Code DTC Detection Condition Trouble Area

C1401

C1402

One of the following conditions is met:


  1. At a vehicle speed of 10 km/h (6 mph) or more, the output voltage from one of the speed sensors is below that from the other sensors for 15 seconds or more.

  2. At a vehicle speed of less than 10 km/h (6 mph), the output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more.

  3. At a vehicle speed of 10 km/h (6 mph) or more, the outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more.

  • Front speed sensor RH/LH

  • Front speed sensor rotor RH/LH

  • Sensor installation

C1271

C1272

 Stored only during test mode.

  • Front speed sensor RH/LH

  • Front speed sensor rotor RH/LH

  • Sensor installation

Tech Tips


  • DTC C1401 is for the front speed sensor RH.

  • DTC C1402 is for the front speed sensor LH.

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. CHECK FRONT SPEED SENSOR INSTALLATION


    1. Turn the ignition switch off.

    2. B001I1RE49
      Text in Illustration
      *1 Front Speed Sensor
      *a No clearance
      *b OK
      *c NG

      Check the speed sensor installation Click here.

      OK
      There is no clearance between the sensor and the front steering knuckle.
      The installation bolt is tightened properly.

    NG

    INSTALL FRONT SPEED SENSOR CORRECTLY Click here

    OK

  2. INSPECT FRONT SPEED SENSOR TIP


    1. Remove the front speed sensor Click here.

    2. Check the speed sensor tip.

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

      Note

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


    NG

    CLEAN OR REPLACE FRONT SPEED SENSOR

    OK

  3. INSPECT FRONT SPEED SENSOR ROTOR


    1. Remove the front axle with ABS rotor bearing assembly Click here.

    2. Check the speed sensor rotor.

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

      Tech Tips

      The front speed sensor rotor is incorporated into the front axle with ABS rotor bearing assembly.

      If the front speed sensor rotor needs to be replaced, replace it together with the front axle with ABS rotor bearing assembly.


    NG

    CLEAN OR REPLACE FRONT SPEED SENSOR ROTOR

    OK

  4. READ VALUE USING INTELLIGENT TESTER (FR/FL WHEEL SPEED)


    1. Turn the ignition switch off

    2. Connect the intelligent tester to the DLC3.

    3. Start the engine.

    4. Turn the intelligent tester on.

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

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      FR Wheel Speed Front speed sensor RH value/ min.: 0 km/h (0 mph), max.: 326 km/h (202 mph) Actual wheel speed No large fluctuations when driving at a constant speed.
      FL Wheel Speed Front speed sensor LH value/ min.: 0 km/h (0 mph), max.: 326 km/h (202 mph) Actual wheel speed No large fluctuations when driving at a constant speed.

    6. 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, refer to the reference chart Click here.

      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).

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

  5. REPLACE FRONT SPEED SENSOR


    1. Turn the ignition switch off.

    2. Replace the front speed sensor Click here.


    NEXT

  6. RECONFIRM DTC


    1. Clear the DTCs 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 output Click here.

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

      Tech Tips

      The front speed sensor rotor is incorporated into the front axle with ABS rotor bearing assembly.

      If the front speed sensor rotor needs to be replaced, replace it together with the front axle with ABS rotor bearing assembly.


    A

    END

    B

    REPLACE FRONT AXLE WITH ABS ROTOR BEARING ASSEMBLY Click here