DTC C1242: G and Yaw Rate Sensor (Longitudinal G Output Data Error)

caution

If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
Do not drop the G and yaw rate sensor or subject it to a shock.
When G and yaw rate sensor is replaced, calibrate G and yaw rate sensor (refer to GROUP 35C - On-vehicle Service ), and initialize the lateral/longitudinal acceleration correction amount stored in AWC-ECU. (Refer to item No.2: Lateral acceleration correction amount initialization, and No.3: Longitudinal acceleration correction amount initialization .)

OPERATION

The G and yaw rate sensor outputs the signal to ASC-ECU and AWC-ECU via the special CAN bus lines.

DTC set conditions

This diagnostic trouble code is set when the abnormality below is detected:

Abnormality in G and yaw rate sensor output value
This diagnostic trouble code is set when AWC-ECU determines that an abnormality is present by comparing the longitudinal G that is output from the G and yaw rate sensor during braking with the calculation value calculated by the data from the wheel speed sensor.

PROBABLE CAUSES

Improper installation of G and yaw rate sensor
Malfunction of G and yaw rate sensor
Malfunction of wheel speed sensor
Malfunction of stoplight switch
Malfunction of AWC-ECU
Malfunction of ASC-ECU

Diagnostic procedure

STEP 1. Scan tool CAN bus diagnostics

Using scan tool MB991958, diagnose the CAN bus lines.

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 DTC is reset.

Q. Is DTC No. C1242 set?

	Go to Step 3.

	This diagnosis is complete.

STEP 3. Scan tool diagnostic trouble code

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

Q. Is the DTC set?

	Perform the relevant troubleshooting.

	Go to Step 4.

STEP 4. Scan tool diagnostic trouble code

Q. Is DTC No. C2204 set?

	Perform the relevant troubleshooting.

	Go to Step 5.

STEP 5. Scan tool diagnostic trouble code

Check if the local CAN communication-related, stoplight switch-related, or wheel speed sensor-related diagnostic trouble code is set.

Q. Is the DTC set?

	Perform the relevant troubleshooting.

	Go to Step 6.

STEP 6. Check of G and yaw rate sensor installation status

Check that the G and yaw rate sensor is installed correctly. (Refer to GROUP 35C - G and Yaw Rate Sensor

Q. Is the check result normal?

	Go to Step 7.

	Reinstall the G and yaw rate sensor correctly. Then go to Step 7.

STEP 7. Scan tool service data

Item No. 31: Longitudinal G sensor (refer to

Q. Is the check result normal?

	Go to Step 8.

	Replace the G and yaw rate sensor. (Refer to GROUP 35C - G and Yaw Rate Sensor .) Then go to Step 8.

STEP 8. Check whether the DTC is reset.

Q. Is DTC No. C1242 set?

	Replace the AWC-ECU.(Refer to .) Then go to Step 9.

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

STEP 9. Check whether the DTC is reset.

Q. Is DTC No. C1242 set?

	Return to Step 1.

	This diagnosis is complete.