Diagnostic Procedure

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

1. STEP 1. Scan tool CAN bus diagnostics 

   Using the scan tool, 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.
2. STEP 2. Scan tool diagnostic trouble code 

   Check the ASC diagnostic trouble code. (Refer to DIAGNOSTIC TROUBLE CODE TABLE .)

   Q: Is the DTC set? 

   1. YES:  Perform the relevant troubleshooting.
   2. NO:  Go to Step 3.
3. STEP 3. Check whether the DTC is reset. 

   After 15 seconds with the engine idle status, check that the DTC is reset.

   Q: Is DTC No. U0121 set? 

   1. YES:  Replace the mechatronic assembly. (Refer to << A >> MECHATRONIC ASSEMBLY REMOVAL .)
   2. NO:  Intermittent malfunction. (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .)