Code No.C123C: G and yaw rate sensor failure <lateral G and yaw rate sensor output value abnormal>

caution

If there is any problem in the CAN bus lines, an incorrect diagnosis code may be stored. Prior to this diagnosis, diagnose the CAN bus lines.
Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
When the steering wheel sensor is replaced, calibrate the steering wheel sensor (Refer to GROUP 35C - On-vehicle Service ), and reset the steering wheel sensor correction amount stored in the 4WD-ECU. (Item No. 1: SAS adjusted value ).
When the hydraulic unit (integrated with ASC-ECU) is replaced, after turning the ignition switch ON or OFF (vehicle information from ETACS-ECU is registered), always carry out the calibration of the steering wheel sensor, the G and yaw rate sensor, and brake fluid pressure sensor.(Refer to GROUP 35C - On-vehicle Service , and .)

OPERATION

The G&yaw rate sensor, which is integrated in the ASC-ECU, sends a signal to the 4WD-ECU via CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is stored when the abnormality below is detected:

Abnormality in G and yaw rate sensor output value
Abnormality is detected by a comparison of output value from the G and yaw rate sensor with the output values from wheel speed sensor and steering wheel sensor.

PROBABLE CAUSES

Malfunction of G and yaw rate sensor
Malfunction of wheel speed sensor
Improper installation of steering wheel sensor
Malfunction of steering wheel sensor
Hydraulic unit improperly installed
Malfunction of 4WD-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.

Use M.U.T.-III to perform the CAN bus diagnosis.

Q. Is the check result normal?

	Go to Step 3

	Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). After repairing the CAN bus line, go to Step 2.

STEP 2. Check whether the diagnosis code is stored again.

Q. Is diagnosis code No.C123C stored?

	Go to Step 3

	This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code.

Check the ASC diagnosis code. (Refer to GROUP 35C - Troubleshooting

Q. Is the check result normal?

	Perform the relevant troubleshooting. (Refer to GROUP 35C - Troubleshooting .)

	Go to Step 4

STEP 4. M.U.T.-III other system diagnosis code.

Check if the wheel speed sensor-related, or steering wheel sensor-related diagnosis code is stored.

Q. Is the diagnosis code stored?

	Perform the relevant troubleshooting.

	Go to Step 5

STEP 5. Check of hydraulic unit (integrated with G and yaw rate sensor) installation status.

Check that the hydraulic unit (integrated with G and yaw rate sensor) is installed correctly <Refer to GROUP 35C - Hydraulic unit (integrated with G and yaw rate sensor)

Q. Is the check result normal?

	Go to Step 6

	Reinstall the hydraulic unit (integrated with G and yaw rate sensor) correctly. Then go to Step 6.

STEP 6. M.U.T.-III data list.

Check the following data list (Refer to

Item No.22: Yaw rate sensor
Item No.23: Lateral G sensor

Q. Is the check result normal?

	Go to Step 7

	Replace the hydraulic unit (integrated with G and yaw rate sensor) is installed correctly (Refer to GROUP 35C - Hydraulic unit (integrated with G and yaw rate sensor) ). Then go to Step 11.

STEP 7. Check of steering wheel sensor installation status.

Check that the steering wheel sensor is installed correctly (Refer to GROUP 35C - Steering Wheel Sensor

Q. Is the check result normal?

	Go to Step 8

	Install the steering wheel sensor correctly. Then go to Step 8.

STEP 8. Wheel alignment check.

GROUP 33 - On-vehicle Service

Q. Is the check result normal?

	After checking the wheel alignment, carry out calibration of steering wheel sensor to make ASC-ECU relearn the neutral point.(Refer to GROUP 35C - On-vehicle Service .) Then go to Step 9.

	After adjusting the wheel alignment, calibrate the steering wheel sensor (Refer to GROUP 35C - On-vehicle Service ), and reset the steering wheel sensor correction amount stored in the 4WD-ECU(Refer to ). Then go to Step 9.

STEP 9. M.U.T.-III data list.

Check the following data list (Refer to

Item No.8: Steering angle sensor

Q. Is the check result normal?

	Go to Step 10

	Replace the steering wheel sensor (Refer to GROUP 35C - Steering Wheel Sensor ). Then go to Step 11.

STEP 10. Check whether the diagnosis code is stored again.

Q. Is diagnosis code No.C123C stored?

	Replace the 4WD-ECU (Refer to ). Then go to Step 11.

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 11. Check whether the diagnosis code is stored again.

Q. Is diagnosis code No.C123C stored?

	Return to Step 1.

	This diagnosis is complete.