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

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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
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DESCRIPTION

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

Tip:

When the connectors between the speed sensor and skid control ECU (master cylinder solenoid) are connected, the following waveform is output.

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 less than 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
Tip:

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

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

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INSPECTION PROCEDURE

Note:

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

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PROCEDURE


  1. Click here

    CHECK FRONT SPEED SENSOR INSTALLATION


    1. Turn the ignition switch off.

    2. A015DN7E49

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

  2. Click here

    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.


  3. Click here

    INSPECT FRONT SPEED SENSOR ROTOR


    1. Remove the front axle hub sub-assembly (Click here).

    2. Check the speed sensor rotor.

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

      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.


  4. Click here

    READ VALUE USING GTS (FR/FL WHEEL SPEED)


    1. Turn the ignition switch off.

    2. Connect the GTS to the DLC3.

    3. Start the engine.

    4. Turn the GTS on.

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

      Table 2. ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      FR Wheel Speed Front speed sensor RH reading/ 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 reading/ 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 GTS and the speed value displayed on the speedometer when driving the vehicle.

      Tip:

      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 GTS is the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).

  5. Click here

    REPLACE FRONT SPEED SENSOR


    1. Replace the front speed sensor (Click here).


  6. Click here

    RECONFIRM DTC


    1. Clear the DTC (Click here).

    2. Turn the ignition switch off.

    3. Start the engine.

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

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

      Table 3. Result
      Result Proceed to
      DTC is not output A
      DTC is output B

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    CHECK FOR INTERMITTENT PROBLEMSClick here

  8. Click here

    END

  9. Click here

    INSTALL FRONT SPEED SENSOR CORRECTLY

  10. Click here

    CLEAN OR REPLACE FRONT SPEED SENSOR

  11. Click here

    CLEAN OR REPLACE FRONT SPEED SENSOR ROTOR

  12. Click here

    REPLACE FRONT AXLE WITH ABS ROTOR BEARING ASSEMBLYClick here