C1271 Low Output Signal of Front Speed Sensor RH (Test Mode DTC)

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Diag Code: 71

CIRCUIT EXPLANATION
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 front and rear rotors has 48 serrations. When the rotors rotate, the magnetic filed 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 rotor, the
frequency is used by the ECU to detect the speed of each wheel. DTCs C1271 and C1272 can be deleted when the speed sensor sends a wheel speed signal or the Test Mode ends. DTCs C1271 and C1272 are output only in the Test Mode.



DTC Code Diag Code DTC Detection Condition Trouble Area
C0200
C0205
31
32
When any of the following is detected:
  1. At a vehicle speed of 10 km/h (6 mph) or more, an open or short in the sensor signal circuit continues for 15 seconds or more.
  2. Momentary interruption of the sensor signal from the
    abnormal wheel occurs 7 times or more.
  3. An open in the speed sensor signal circuit continues for 0.5 seconds or more.
  4. When the following condition occurs 4 or more times after the ignition switch is turned off:
    The speeds of the front wheels are lower than the rear
    wheel speed by 20 km/h (12 mph) or more for 20 seconds
    or more.
• Front speed sensor RH/LH
• Speed sensor circuit
• Speed sensor rotor
• Sensor installation
• Skid control ECU
C1271
C1272
71
72
Detected only during Test Mode. • Front speed sensor RH/LH
• Sensor installation
• Speed sensor rotor

• DTCs C0200 and C1271 are for the front speed sensor RH.
• DTCs C0205 and C1272 are for the front speed sensor LH.


WIRING DIAGRAM



INSPECTION PROCEDURE

1.PERFORM TEST MODE (SIGNAL CHECK)

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2.RECONFIRM DTC

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3.CHECK FRONT SPEED SENSOR INSTALLATION

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4.CHECK FRONT SPEED SENSOR TIP

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5.INSPECT FRONT SPEED SENSOR

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

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7.CHECK SPEED SENSOR AND SPEED SENSOR ROTOR SERRATIONS

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8.RECONFIRM DTC

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9.DTC Clear

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