Foreign Object is Attached on Tip of Front Speed Sensor RH - Electronically Controlled Brake System
BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1235/35, C1236/36, C1238/38, C1239/39, C1275/75-C1278/78: Foreign Object is Attached on Tip of Front Speed Sensor RH
C1278/78 - Abnormal Change in Output Signal of Rear Speed Sensor LH (Test Mode DTC)
DESCRIPTION
When foreign matter adheres to the speed sensor tip or speed sensor rotor, 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 C1275/75 to C1278/78 will be cleared when the speed sensor sends a wheel speed signal or when Test Mode ends. DTCs from C1275/75 to C1278/78 are output only in Test Mode.
HINT
* DTCs C1235/35 and C1275/75 are for the front speed sensor RH.
* DTCs C1236/36 and C1276/76 are for the front speed sensor LH.
* DTCs C1238/38 and C1277/77 are for the rear speed sensor RH.
* DTCs C1239/39 and C1278/78 are for the rear speed sensor LH.
WIRING DIAGRAM
Refer to DTCs C1464/31, C1465/32, C1466/33 and C1467/34 C1272 for front, and C1466 for rear).
INSPECTION PROCEDURE
NOTICE:
When replacing the skid control ECU, perform initialization and calibration of the linear solenoid valve Initialization.
HINT
When C1464/31, C1465/32, C1466/33, and/or C1467/34 is output together with C1235/35, C1236/36, C1238/38, and/or C1239/39, inspect and repair the trouble areas indicated by C1464/31, C1465/32, C1466/33, and/or C1467/34 first C1272 for front, or C1466 for rear).
PROCEDURE
1. CHECK SPEED SENSOR AND SPEED SENSOR ROTOR SERRATIONS
(a) Connect an oscilloscope to each speed sensor terminal of the skid control ECU and body ground.
(b) Check the waveform output when the wheels are rotated.
OK:
The same waveform is output from all the sensors and there is no noise or interference in the waveform.
(c) Check that the waveform does not change while jiggling a connector or a wire harness.
OK:
The waveform does not change.
Text in Illustration
HINT
* As the vehicle speed (wheel revolution speed) increases, the wavelength shortens.
* When noise is identified in the waveform on the oscilloscope, the erratic signals are generated due to speed sensor rotor scratches, looseness or attached foreign matter.
NG -- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - SPEED SENSOR)
OK -- Continue to next step.
2. RECONFIRM DTC
(a) Turn the ignition switch off.
(b) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(c) Turn the ignition switch to ON (READY).
(d) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 15 seconds.
(e) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
Result:
B -- REPLACE SKID CONTROL ECU Removal
A -- RECONFIRM DTC
3. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - SPEED SENSOR)
(a) Turn the ignition switch off.
Text in Illustration
(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.
(c) Disconnect the A44, A45, A46 or A47 skid control ECU connector.
(d) Disconnect the A12, A29, N20 or O39 speed sensor connector.
(e) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
for RH
for LH
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK SPEED SENSOR TIP
(a) Turn the ignition switch off.
(b) Remove the front or rear speed sensor Removal for front, or Removal for rear).
(c) Check the speed sensor tip.
OK:
The sensor tip is free of scratches, oil, and foreign matter.
NOTICE:
* If no damage to the speed sensor tip is found during this inspection, do not replace the speed sensor.
* Check the speed sensor signal after cleaning or replacement Test Mode Procedure.
NG -- CLEAN OR REPLACE SPEED SENSOR
OK -- Continue to next step.
5. CHECK SPEED SENSOR ROTOR
(a) Remove the front or rear speed sensor rotor Removal for front, or Removal for rear).
(b) Check the speed sensor rotor.
OK:
The sensor rotor is free of scratches, oil, and foreign matter.
HINT
* If the front speed sensor rotor needs to be replaced, replace it together with the front drive outboard joint shaft assembly.
* If the rear speed sensor rotor needs to be replaced, replace it together with the outboard joint shaft assembly.
NOTICE:
Check the speed sensor signal after cleaning or replacement Test Mode Procedure.
NG -- CLEAN OR REPLACE SPEED SENSOR ROTOR
OK -- Continue to next step.
6. RECONFIRM DTC
(a) Install the speed sensor and the speed sensor rotor.
(b) Reconnect the skid control ECU connectors and the speed sensor connectors.
(c) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(d) Turn the ignition switch to ON (READY).
(e) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 15 seconds.
(f) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
Result:
B -- CHECK FOR INTERMITTENT PROBLEMS How To Proceed With Troubleshooting
A -- Continue to next step.
7. REPLACE SPEED SENSOR
(a) Turn the ignition switch off.
(b) Replace the front speed sensor and the rear speed sensor Removal for front, or Removal for rear).
NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.
NEXT -- Continue to next step.
8. RECONFIRM DTC
(a) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(b) Turn the ignition switch to ON (READY).
(c) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 15 seconds.
(d) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
Result:
B -- END
A -- Continue to next step.
9. REPLACE SPEED SENSOR ROTOR
(a) Turn the ignition switch off.
(b) Remove the front drive shaft assembly or the rear drive shaft assembly Removal for front, or Removal for rear).
(c) Replace the front drive outboard joint shaft assembly (front speed sensor rotor) or the outboard joint shaft assembly (rear speed sensor rotor) Disassembly for front, or Disassembly for rear).
HINT
* If the front speed sensor rotor needs to be replaced, replace it together with the front drive outboard joint shaft assembly.
* If the rear speed sensor rotor needs to be replaced, replace it together with the outboard joint shaft assembly.
NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.
NEXT -- Continue to next step.
10. RECONFIRM DTC
(a) Install the drive shaft assembly (for front).
(b) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(c) Turn the ignition switch to ON (READY).
(d) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 15 seconds.
(e) Check if the same DTC is recorded Reading and Clearing Diagnostic Trouble Codes.
Result:
B -- END
A -- REPLACE SKID CONTROL ECU Removal