DTC U0154: OCM (Occupant Classification-ECU) CAN Timeout: Diagnosis

Required Special Tools: 

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: Vehicles Communication Interface (V.C.I.)
  • MB991827 M.U.T.-III USB Cable
  • MB991910 M.U.T.-III Main Harness A (Vehicles with CAN communication system)

1. STEP 1. Using scan tool MB991958, diagnose the CAN bus line. 
   CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
   1. Connect scan tool MB991958. Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)  ."
   2. Turn the ignition switch to the "ON" position.
   3. Diagnose the CAN bus line.
   4. Turn the ignition switch to the "LOCK" (OFF) position.

      Q: Is the CAN bus line found to be normal? 

      • YES:  Go to Step 2.
      • NO:  Repair the CAN bus line (Refer to PRECAUTIONS ON HOW TO REPAIR THE CAN BUS LINES ).
        Fig 1: Connecting Scan Tool To Data Link Connector

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Using scan tool MB991958, read the occupant classification-ECU diagnostic trouble code. 

   Check if DTC is set to the occupant classification-ECU.

   Q: Is the DTC set? 

   • YES:  Troubleshoot the SRS (Refer to SRS AIR BAG DIAGNOSIS ).
   • NO:  Go to Step 3.
3. STEP 3. Using scan tool MB991958, read the combination meter diagnostic trouble code. 

   Check if the DTC U0154 is set to the combination meter.

   Q: Is the DTC set? 

   • YES:  Go to Step 4.
   • NO:  Go to  Step 5.
4. STEP 4. Recheck for diagnostic trouble code. 

   Check again if the DTC is set to the CAN box unit.

   1. Erase the DTC.
   2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
   3. Check if DTC is set.
   4. Turn the ignition switch to the "LOCK" (OFF) position.

      Q: Is the DTC set? 

      • YES:  Replace the occupant classification-ECU.
      • NO:  The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the occupant classification-ECU and the CAN box unit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
5. STEP 5. Recheck for diagnostic trouble code. 

   Check again if the DTC is set to the CAN box unit.

   1. Erase the DTC.
   2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
   3. Check if DTC is set.
   4. Turn the ignition switch to the "LOCK" (OFF) position.

      Q: Is the DTC set? 

      • YES:  Replace the CAN box unit.
      • NO:  The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the occupant classification-ECU and the CAN box unit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).