C1274 Low Output Signal of Rear Speed Sensor LH (Test Mode DTC)

1. Perform sensor check in the Test Mode procedure (See page TEST MODE PROCEDURE).
   
   OK: All Test Mode DTCs are not output.

Go to step 3

[2] RECONFIRM DTC

1. Turn the ignition switch off.
2. Clear the DTC (See Pub. No. S1-YXZE05A, page 05-108).
3. Start the engine.
4. Drive the vehicle at the speed of 20 km/h (12 mph) or more for at least 30 seconds.
5. Check if the same DTC is recorded (See Pub. No. S1- YXZE05A, page 05-108).
   
   Result:

   Result	Proceed to
   DTCs (C0210 and/or C0215) are not output	A
   DTCs (C0210 and/or C0215) 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

1. Turn the ignition switch off.
2. Check the speed sensor installation.
   
   OK: There is no clearance between the sensor and the rear axle carrier.
        The installation bolt is tightened properly.
   Torque: 8.0 N*m (82 kgf*cm, 71 in.*lbf)
   
   

　

INSTALL REAR SPEED SENSOR CORRECTLY

[4] CHECK REAR SPEED SENSOR TIP

1. Remove the rear speed sensor (See Pub. No. S1- YXZE05A, SPEED SENSOR REAR LH).
2. 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 REAR SPEED SENSOR

[5] INSPECT REAR SPEED SENSOR

1. Turn the ignition switch off.
2. Install the rear speed sensor.
3. Disconnect the rear speed sensor connector.
4. Measure the resistance according to the value (s) in the table below.
   
   
   
   Standard resistance:
   for RH

   Tester Connection	Condition	Specified Condition
   1 (RR+) - 2 (RR-)	Always	1.4 to 1.8 kΩ at 20ºC (68ºF)
   1 (RR+) - Body ground	Always	10 kΩ or higher
   2 (RR-) - Body ground	Always	10 kΩ or higher

   
   for LH

   Tester Connection	Condition	Specified Condition
   1 (RL+) - 2 (RL-)	Always	1.4 to 1.8 kΩ at 20ºC (68ºF)
   1 (RL+) - Body ground	Always	10 kΩ or higher
   2 (RL-) - Body ground	Always	10 kΩ or higher

   
   Check the speed sensor signal after replacement (See TEST MODE PROCEDURE).
   

REPLACE REAR SPEED SENSOR

[6] CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - REAR SPEED SENSOR)

1. Disconnect the skid control ECU connector.
2. Measure the resistance according to the value (s) in the table below.
   
    
   Standard resistance:
   for RH

   Tester Connection	Condition	Specified Condition
   S13-16 (RR+) - A16-1 (RR+)	Always	Below 1Ω
   S13-16 (RR+) - Body ground	Always	10 kΩ or higher
   S13-15 (RR-) - A16-2 (RR-)	Always	Below 1Ω
   S13-15 (RR-) - Body ground	Always	10 kΩ or higher

   
   for LH

   Tester Connection	Condition	Specified Condition
   S13-22 (RL+) - A15-1 (RL+)	Always	Below 1Ω
   S13-22 (RL+) - Body ground	Always	10 kΩ or higher
   S13-23 (RL-) - A15-2 (RL-)	Always	Below 1Ω
   S13-23 (RL-) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

[7] CHECK SPEED SENSOR AND SPEED SENSOR ROTOR SERRATIONS

1. Reconnect the skid control ECU connector and the rear speed sensor connector.
2. Connect the oscilloscope to the rear speed sensor terminal of the skid control ECU.
3. 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

1. Turn the ignition switch off.
2. Clear the DTC (See Pub. No. S1-YXZE05A, page 05-108).
3. Start the engine.
4. Drive the vehicle at the speed of 20 km/h (12 mph) or more for at least 30 seconds.
5. Check if the same DTC is recorded (See Pub. No. S1- YXZE05A, page 05-108).
   
   Result:

   Result	Proceed to
   DTCs (C0210 and/or C0215) are not output	A
   DTCs (C0210 and/or C0215) 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

1. Confirm the DTC C1274 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC C1274 is inactive.

   

2. DTC Clear

   • Clear the DTC with Hino DX
   • Confirm the same DTC is not reoccurred

   

C1274 is reoccur: Return to first process Other DTC appear: Refer to concerned Trouble shooting

Complete