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 scan tool MB991958, diagnose the CAN bus lines.

   Q: Is the check result normal? 

   1. YES:  Check and repair the TC-SST-ECU power supply circuit. (Refer to INSPECTION PROCEDURE 4: TC-SST-ECU POWER SUPPLY CIRCUIT MALFUNCTION  .)
   2. NO:  Repair the CAN bus lines. (Refer to TROUBLESHOOTING .)