Abnormal Change in Output Signal of Front Speed Sensor LH (Test Mode DTC) - Vehicle Stability Control System (w/ VDIM)

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM (w/ VDIM): C1235/35: Foreign Object is Attached on Tip of Front Speed Sensor RH

DTC C1235/35 - Foreign Object is Attached on Tip of Front Speed Sensor RH

DTC C1236/36 - Foreign Object is Attached on Tip of Front Speed Sensor LH

DTC C1238/38 - Foreign Object is Attached on Tip of Rear Speed Sensor RH

DTC C1239/39 - Foreign Object is Attached on Tip of Rear Speed Sensor LH

DTC C1275/75 - Abnormal Change in Output Signal of Front Speed Sensor RH (Test Mode DTC)

DTC C1276/76 - Abnormal Change in Output Signal of Front Speed Sensor LH (Test Mode DTC)

DTC C1277/77 - Abnormal Change in Output Signal of Rear Speed Sensor RH (Test Mode DTC)

DTC C1278/78 - Abnormal Change in Output Signal of Rear Speed Sensor LH (Test Mode DTC)

DESCRIPTION

The speed sensor detects wheel speed and sends the appropriate signals to the skid control ECU. These signals are used for the ABS control system. This speed sensor contains a sensor IC, which consists of 2 MREs (Magnetic Resistance Element). The speed sensor rotor, which consists of 48 sets of N and S poles that are arranged in a circle, is integrated with the inner race of the hub bearing.
To detect the rotation direction, the output waves are used to determine the relationship of the pulses that are generated by 2 MREs. Upon receiving this signal, the sensor IC outputs a forward or backward wave to the ECU.
DTCs C1275/75 to C1278/78 can be deleted when the speed sensor sends a vehicle speed signal or the Test Mode ends. DTCs C1275/75 to C1278/78 are output only in the Test Mode.

HINT:
- DTC C1235/35 is for the front speed sensor RH.
- DTC C1236/36 is for the front speed sensor LH.
- DTC C1238/38 is for the rear speed sensor RH.
- DTC C1239/39 is for the rear speed sensor LH.

WIRING DIAGRAM

INSPECTION PROCEDURE
NOTE: When replacing the skid control ECU, perform zero point calibration and store system information Vehicle Stability Control System (W/ VDIM).

HINT: When C0200/31, C0205/32, C0210/33 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, or C0215/34 first.

PROCEDURE

1. CHECK SENSOR AND SENSOR ROTOR SERRATIONS

(a) Connect the oscilloscope to terminals FR-, FL-, RR-, and RL- of the skid control ECU and body ground.
(b) Check the signal waveform.
OK:
The same waveform is output from all the 4 wheels and there is no noise or interference in the waveform.
(c) Check that the waveform does not change while jiggling a connector or wire harness.
OK:
The waveform does not change.

HINT:
- As the vehicle speed (wheel revolution speed) increases, a cycle of the waveform narrows and the fluctuation in the output voltage becomes greater.
- When noise is identified in the waveform on the oscilloscope, error signals are generated due to the speed sensor rotor's scratches, looseness or foreign matter attached to it.

NG -- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - EACH SPEED SENSOR)
OK -- Continue to next step.
2. RECONFIRM DTC
(a) Clear the DTC Vehicle Stability Control System (w/ VDIM).
(b) Start the engine.
(c) Drive the vehicle at the speed of 12 mph (20 km/h) or more for at least 60 seconds.
(d) Check if the same DTC is recorded Vehicle Stability Control System (w/ VDIM).
Result:

B -- REPLACE SKID CONTROL ECU
A -- USE SIMULATION METHOD TO CHECK
3. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - EACH SPEED SENSOR)

(a) Disconnect the skid control ECU connector and each speed sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
RH

Result:

C -- REPAIR OR REPLACE HARNESS OR CONNECTOR
B -- CHECK EACH SPEED SENSOR ROTOR
A -- Continue to next step.
4. CHECK REAR SPEED SENSOR TIP
(a) Remove the rear speed sensor Removal.
(b) Check the speed sensor tip.
OK:
No scratches or foreign matter on the sensor tip.
NOTE: Check the speed sensor signal after cleaning/replacement Test Mode Procedure.

NG -- CLEAN OR REPLACE REAR SPEED SENSOR
OK -- Continue to next step.
5. CHECK EACH SPEED SENSOR ROTOR
(a) Remove each speed sensor rotor.
(b) Check the speed sensor rotor.
OK:
No scratches, oil, or foreign matter on the rotors.
NOTE: Check the speed sensor signal after cleaning/replacement Test Mode Procedure.

NG -- CLEAN OR REPLACE EACH SPEED SENSOR ROTOR
OK -- Continue to next step.
6. RECONFIRM DTC
(a) Install the rear speed sensor and the speed sensor rotor.
(b) Reconnect the skid control ECU connector and the speed sensor connector.
(c) Clear the DTC Vehicle Stability Control System (w/ VDIM).
(d) Start the engine.
(e) Drive the vehicle at the speed of 12 mph (20 km/h) or more for at least 60 seconds.
(f) Check if the same DTC is recorded Vehicle Stability Control System (w/ VDIM).
Result:

B -- USE SIMULATION METHOD TO CHECK
A -- Continue to next step.
7. REPLACE EACH SPEED SENSOR
(a) Turn the engine switch off.
(b) Replace each speed sensor Removal for front, or Removal for rear).
NOTE: Check the speed sensor signal after replacement Test Mode Procedure.

NEXT -- Continue to next step.
8. RECONFIRM DTC
(a) Clear the DTC Vehicle Stability Control System (w/ VDIM).
(b) Start the engine.
(c) Driver the vehicle at the speed of 12 mph (20 km/h) or more for at least 60 seconds.
(d) Check if the same DTC is recorded Vehicle Stability Control System (w/ VDIM).
Result:

B -- END
A -- REPLACE SKID CONTROL ECU