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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:
abnormal wheel occurs 7 times or more. 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 |
WIRING DIAGRAM
INSPECTION PROCEDURE
Detail
- Perform sensor check in the Test Mode procedure (See TEST MODE PROCEDURE).
OK: All Test Mode DTCs are not output.
Go to step 3
[2] RECONFIRM DTC
- Turn the ignition switch off.
- Clear the DTC (See Pub. No. S1-YXZE05A, page 05-108).
- Start the engine.
- Drive the vehicle at the speed of 20 km/h (12 mph) or more for at least 30 seconds.
- Check if the same DTC is recorded (See Pub. No. S1- YXZE05A, page 05-108).
Result:
Result Proceed to DTCs (C0200 and/or C0205) are not output A DTCs (C0200 and/or C0205) are output B
If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (See PROBLEM SYMPTOMS TABLE).
A
CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) (See DIAGNOSIS SYSTEM)B
Go to step 5
- Turn the ignition switch off.
- Check the speed sensor installation.
OK: There is no clearance between the sensor and the front steering knuckle.
The installation bolt is tightened properly.
Torque: 8.0 N*m (82 kgf*cm, 71 in.*lbf)
INSTALL FRONT SPEED SENSOR CORRECTLY
[4] CHECK FRONT SPEED SENSOR TIP
- Remove the front speed sensor (See Pub. No. S1- YXZE05A, SPEED SENSOR FRONT LH).
Check the speed sensor tip.
OK: No scratches or foreign matter on the sensor tip.
Check the speed sensor signal after cleaning or replacement (See TEST MODE PROCEDURE).
CLEAN OR REPLACE FRONT SPEED SENSOR
[5] INSPECT FRONT SPEED SENSOR
- Turn the ignition switch off.
- Install the front speed sensor.
- Disconnect the front speed sensor connector.
- Measure the resistance according to the value (s) in the table below.
Standard resistance:
for RH
Tester Connection Condition Specified Condition 1 (FR+) - 2 (FR-) Always 0.9 to 1.3 kΩ at 20ºC (68ºF) 1 (FR+) - Body ground Always 10 kΩ or higher 2 (FR-) - Body ground Always 10 kΩ or higher
for LH
Tester Connection Condition Specified Condition 1 (FL+) - 2 (FL-) Always 0.9 to 1.3 kΩ at 20ºC (68ºF) 1 (FL+) - Body ground Always 10 kΩ or higher 2 (FL-) - Body ground Always 10 kΩ or higher
Check the speed sensor signal after replacement (See TEST MODE PROCEDURE).
REPLACE FRONT SPEED SENSOR
[6] CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - FRONT SPEED SENSOR)
- Disconnect the skid control ECU connector.
- Measure the resistance according to the value (s) in the table below.
Standard resistance:
for RH
Tester Connection Condition Specified Condition S14-26 (FR+) - A3-1 (FR+) Always Below 1Ω S14-26 (FR+) - Body ground Always 10 kΩ or higher S14-25 (FR-) - A3-2 (FR-) Always Below 1Ω S14-25 (FR-) - Body ground Always 10 kΩ or higher
for LH
Tester Connection Condition Specified Condition S14-27 (FL+) - A2-1 (FL+) Always Below 1Ω S14-27 (FL+) - Body ground Always 10 kΩ or higher S14-28 (FL-) - A2-2 (FL-) Always Below 1Ω S14-28 (FL-) - Body ground Always 10 kΩ or higher
REPAIR OR REPLACE HARNESS OR CONNECTOR
[7] CHECK SPEED SENSOR AND SPEED SENSOR ROTOR SERRATIONS
- Reconnect the skid control ECU connector and the front speed sensor connector.
- Connect the oscilloscope to the front speed sensor terminal of the skid control ECU.
- Check that a waveform is output by each sensor circuit when the tires are rotated.
OK:
The same waveform is output from all the 4 wheels and there is no noise or interference in the waveform.
- As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the output voltage becomes greater.
- When noise is identified in the waveform on the oscilloscope, the erratic signals are generated due to speed sensor rotor's scratches, looseness or foreign matter attached to it.
Check the speed sensor signal after cleaning or replacement (See TEST MODE PROCEDURE).
CLEAN OR REPLACE SPEED SENSOR OR SPEED SENSOR ROTOR
[8] RECONFIRM DTC
- Turn the ignition switch off.
- Clear the DTC (See Pub. No. S1-YXZE05A, page 05-108).
- Start the engine.
- Drive the vehicle at the speed of 20 km/h (12 mph) or more for at least 30 seconds.
- Check if the same DTC is recorded (See Pub. No. S1- YXZE05A, page 05-108).
Result:
Result Proceed to DTCs (C0200 and/or C0205) are not output A DTCs (C0200 and/or C0205) are output B
If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (See PROBLEM SYMPTOMS TABLE).
A
CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) (See DIAGNOSIS SYSTEM)B
REPLACE SKID CONTROL ECU
- Confirm the DTC C1271 is inactive
- Start the engine and let it idling condition.
- Verify the DTC C1271 is inactive.
- DTC Clear
- Clear the DTC with Hino DX
- Confirm the same DTC is not reoccurred
- C1271 is reoccur: Return to first process
- Other DTC appear: Refer to concerned Trouble shooting
Complete
