C1277  Abnormal Change in Output Signal of Rear Speed Sensor RH (Test Mode DTC)

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Diag Code: 77

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 front and rear rotors 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 rotor, the
frequency is used by the ECU to detect the speed of each wheel.
When foreign matter adheres to the speed sensor tip or speed sensor rotor, or the rotor teeth are chipped,
these DTCs are output. An abnormal waveform input from the sensor determines these conditions.
These DTCs may be detected when a malfunction occurs in the connector terminals or wire harness of
the speed sensor circuit. DTCs C1275 to C1278 can be deleted when the speed sensor sends a vehicle speed signal or the Test Mode ends. DTCs from C1275 to C1278 are output only in the Test Mode.



DTC Code Diag Code DTC Detection Condition Trouble Area
C1235
C1236
C1238
C1239
35
36
38
39
When either of the following is detected:
  1. At a vehicle speed of 20 km/h (12 mph) or more, noise
    occurs in the sensor signal from the abnormal wheel for
    5 seconds or more.
  2. When the vehicle starts off, the condition that the speed of any wheel is 7 km/h (4.3 mph) or more occurs 3 times or more.
• Speed sensor
• Speed sensor rotor
• Sensor installation
• Skid control ECU
C1275
C1276
C1277
C1278
75
76
77
78
Detected only during Test Mode. • Speed sensor
• Speed sensor rotor


• DTCs C1235 and C1275 are for the front speed sensor RH.
• DTCs C1236 and C1276 are for the front speed sensor LH.
• DTCs C1238 and C1277 are for the rear speed sensor RH.
• DTCs C1239 and C1278 are for the rear speed sensor LH.

WIRING DIAGRAM



INSPECTION PROCEDURE


When C0200, C0205, C0210, and/or C0215 is output together with C1235, C1236, C1238, and/or C1239, inspect and repair the trouble areas indicated by C0200, C0205, C0210, and/or C0215 first (See C0200, C0205 for front, or C0210, C0215 for rear).

1.CHECK SPEED SENSOR AND SPEED SENSOR ROTOR SERRATIONS

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2.RECONFIRM DTC.

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3.INSPECT EACH SPEED SENSOR

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4.CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - EACH SPEED SENSOR)

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5.RECONFIRM DTC

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6.CHECK EACH SPEED SENSOR INSTALLATION

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7.CHECK EACH SPEED SENSOR TIP

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8.CHECK EACH SPEED SENSOR ROTOR

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9.RECONFIRM DTC

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10.DTC Clear

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