Diagnostic Procedure

STEP 1. Scan tool CAN bus diagnostics
Using scan tool MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?
1. YES: Go to Step 2.
2. NO: Repair the CAN bus lines. (Refer to TROUBLESHOOTING .) After repairing the CAN bus line, go to Step 2.
STEP 2. Scan tool diagnostic trouble code
Check the engine diagnostic trouble code. (Refer to TROUBLESHOOTING .)

Q: Is the DTC set?
1. YES: Perform the relevant troubleshooting.
2. NO: Go to Step 3.
STEP 3. Check whether the DTC is reset.
Q: Is DTC No. U0100 set?
1. YES: Replace the AWC-ECU. (Refer to AWC-ECU .) Then go to Step 4.
2. NO: Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)
STEP 4. Check whether the DTC is reset.
Q: Is DTC No. U0100 set?
1. YES: Return to Step 1.
2. NO: This diagnosis is complete.