U0431

DTC U0431: ETACS 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.

OPERATION
AWC-ECU communicates with the ETACS-ECU via the CAN bus lines.

DTC SET CONDITIONS
The code is set when abnormality is detected in the signal received from the ETACS-ECU.

PROBABLE CAUSES
^ The CAN bus line is defective.
^ Malfunction of the ETACS-ECU
^ Malfunction of AWC-ECU

DIAGNOSIS

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 2.
NO: Repair the CAN bus lines. (Refer to Troubleshooting CAN Bus Diagnostics Table).

STEP 2. Scan tool diagnostic trouble code
Check the ETACS diagnostic trouble code. (Refer to Troubleshooting Diagnostic Trouble Code Descriptions).
Q: Is the DTC set?
YES: Perform the relevant troubleshooting.
NO: Go to Step 3.

STEP 3. Scan tool data list
Check the following data list. (Refer to data list reference table Data List Reference Table).
^ Item No. 39: Stoplight switch
^ Item No. 43: Battery positive voltage
Q: Is the check result normal?
YES: Intermittent malfunction. (Refer to How to Cope with Intermittent Malfunction How to Use Troubleshooting/Inspection Service Points).
NO: Go to Step 4.

STEP 4. Check whether the DTC is reset.
Q: Is DTC No. U0431 set?
YES: Replace the AWC-ECU. Then go to Step 5.
NO: Intermittent malfunction. (Refer to How to Cope with Intermittent Malfunction How to Use Troubleshooting/Inspection Service Points).

STEP 5. Check whether the DTC is reset.
Q: Is DTC No. U0431 set?
YES: Return to Step 1.
NO: This diagnosis is complete.