ASC

DTC C1242: Abnormality in G and yaw rate sensor (longitudinal G sensor)

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.

CIRCUIT OPERATION
^ ASC-ECU supplies power to the G and yaw rate sensor at the terminal No. 1.
^ The G and yaw rate sensor outputs the signal to ASC-ECU via the special CAN bus lines.

DTC SET CONDITIONS
This diagnostic trouble code is set when the abnormality is detected by comparing the longitudinal G-sensor value output from the G and yaw rate sensor with the value output from the wheel speed sensor.

PROBABLE CAUSES
^ Improper installation of the G and yaw rate sensor
^ G and yaw rate sensor malfunction
^ Malfunction of wheel speed sensor
^ ASC-ECU malfunction
^ External noise interference

DIAGNOSIS

Required Special Tools:
^ MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A

STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC C1242 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Check the wheel speed sensor-related diagnostic trouble code.
Use scan tool to check whether the wheel speed sensor-related diagnostic trouble code is set or not.
Q: Is any DTC set?
YES: Troubleshoot for the relevant diagnostic trouble code.
NO: Go to Step 4.

STEP 4. G and yaw rate sensor check
Check that the G and yaw rate sensor is installed correctly.
Q: Is the check result normal?
YES: Go to Step 5.
NO: Reinstall the G and yaw rate sensor correctly.

STEP 5. M.U.T.-III data list
Check the following service data.
^ Item 09: G sensor

Q: Is the check result normal?
YES: Go to Step 6.
NO: Replace the G and yaw rate sensor, and then go to Step 6.

STEP 6. Check whether the diagnostic trouble code is reset.
Q: Is DTC C1242 set?
YES: Replace the ASC-ECU.
NO: The procedure is complete.