Abnormal Change in Output Signal of Front Speed Sensor LH (Test Mode DTC) - ABS (Antilock Brake System)

BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ANTI-LOCK 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

The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU. These signals are used for the ABS control system.

Speed sensor rotors have 48 serrations (for front) or rows of alternating N and S magnetic poles (for rear). The hall IC type speed sensor use the frequency of output pulses to detect the vehicle speed. Because the sensor outputs digital pulses, it can detect vehicle speeds even when the vehicle is nearly stationary.

When foreign matter or oil 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 deleted when the speed sensor sends a vehicle speed signal or when Test Mode ends. DTCs 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





INSPECTION PROCEDURE

HINT
When C0200/31, C0205/32, C0210/33 and/or C0215/34 is output together with C1235/35, C1236/36, C1238/38, or C1239/39, inspect and repair the trouble areas indicated by C0200/31, C0205/32, C0210/33 and/or C0215/34 first Front Speed Sensor RH Circuit - ABS (Antilock Brake System) for front, or DTC 33 for rear).

PROCEDURE

1. INSPECT SPEED SENSOR

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.





(b) Disconnect each speed sensor connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

for RH
for LH










Result:





NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.

C -- REPLACE SPEED SENSOR

B -- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - SPEED SENSOR)
A -- Continue to next step.

2. CHECK HARNESS AND CONNECTOR (SKID CONTROL SENSOR WIRE)

(a) Disconnect the skid control sensor wire.





(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

for RH
for LH










NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.

NG -- REPLACE SKID CONTROL SENSOR WIRE
OK -- Continue to next step.

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

(a) Reconnect the skid control sensor wire.





(b) Disconnect the skid control ECU connector.

(c) 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. INSPECT SKID CONTROL ECU (SENSOR INPUT)

(a) Reconnect the skid control ECU connector.





(b) Turn the ignition switch to ON.

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

for RH
for LH










NG -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal
OK -- Continue to next step.

5. RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Reconnect the speed sensor connector.

(c) Clear the DTCs ABS (Antilock Brake System).

(d) Start the engine.

(e) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 60 seconds.

(f) Check if the same DTC is recorded ABS (Antilock Brake System).

Result:





C -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Diagnosis System

B -- REPLACE REAR SPEED SENSOR AND REAR SPEED SENSOR ROTOR
A -- Continue to next step.

6. CHECK FRONT SPEED SENSOR TIP

(a) Turn the ignition switch off.

(b) Remove the front speed sensor Removal.

(c) Check the speed sensor tip.

OK:

No scratches or foreign matter on the sensor tip.

NOTICE:
Check the speed sensor signal after cleaning or replacement Test Mode Procedure.

NG -- CLEAN OR REPLACE FRONT SPEED SENSOR
OK -- Continue to next step.

7. CHECK FRONT SPEED SENSOR ROTOR

(a) Remove the front speed sensor rotor Removal.

(b) Check the speed sensor rotors.

OK:

No scratches, oil, or foreign matter on the rotors.

NOTICE:
Check the speed sensor signal after cleaning or replacement Test Mode Procedure.

HINT
If the front speed sensor rotor needs to be replaced, replace it together with the front axle outboard joint shaft assembly.

NG -- CLEAN OR REPLACE FRONT SPEED SENSOR ROTOR
OK -- Continue to next step.

8. RECONFIRM DTC

(a) Install the front speed sensor and the front speed sensor rotor.

(b) Clear the DTCs ABS (Antilock Brake System).

(c) Start the engine.

(d) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 60 seconds.

(e) Check if the same DTC is recorded ABS (Antilock Brake System).

Result:





B -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Diagnosis System
A -- Continue to next step.

9. REPLACE FRONT SPEED SENSOR

(a) Turn the ignition switch off.

(b) Replace the front speed sensor Removal.

NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.

NEXT -- Continue to next step.

10. RECONFIRM DTC

(a) Clear the DTCs ABS (Antilock Brake System).

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 60 seconds.

(d) Check if the same DTC is recorded ABS (Antilock Brake System).

Result:





B -- END
A -- Continue to next step.

11. REPLACE FRONT SPEED SENSOR ROTOR

(a) Turn the ignition switch off.

(b) Remove the front drive shaft assembly Removal.

(c) Replace the front axle outboard joint shaft assembly (front speed sensor rotor) Disassembly.

HINT
If the front speed sensor rotor needs to be replaced, replace it together with the front axle outboard joint shaft assembly.

NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.

NEXT -- Continue to next step.

12. RECONFIRM DTC

(a) Install the front drive shaft assembly.

(b) Clear the DTCs ABS (Antilock Brake System).

(c) Start the engine.

(d) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 60 seconds.

(e) Check if the same DTC is recorded ABS (Antilock Brake System).

Result:





B -- END

A -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal

13. REPLACE REAR SPEED SENSOR AND REAR SPEED SENSOR ROTOR

(a) Turn the ignition switch off.

(b) Replace the rear speed sensor Removal.

(c) Replace the rear axle hub and bearing assembly (rear speed sensor rotor) Removal.

HINT
The rear speed sensor rotor is incorporated into the rear axle hub and bearing assembly.

If the rear speed sensor rotor needs to be replaced, replace it together with the rear axle hub and bearing assembly with rear speed sensor.

NOTICE:
Check the speed sensor signal after replacement Test Mode Procedure.

NEXT -- Continue to next step.

14. RECONFIRM DTC

(a) Clear the DTCs ABS (Antilock Brake System).

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 60 seconds.

(d) Check if the same DTC is recorded ABS (Antilock Brake System).

Result:





B -- END

A -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal