DTC B2409: STL unit comm. (No response): 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 to the data link connector.
   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? 

   1. YES:  Go to Step 2.
   2. NO:  Repair the CAN bus line. (Refer to DIAGNOSIS ).
      Fig 1: Connecting Scan Tool MB991958 To Data Link Connector

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. STEP 2. Check key reminder switch connector C-213 and KOS-ECU connector C-31 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is the key reminder switch connector C-213 and KOS-ECU connector C-31 in good condition? 

   1. YES:  Go to Step 3.
   2. NO:  Repair the defective connector.
3. STEP 3. Check the wiring harness between the key reminder switch connector C-213 (terminal No. 12, 9, 11) and the KOS-ECU connector C-31 (terminal No. 4, 5, 31). 
   • Check the signal lines for open circuit and short circuit.

   Q: Is the wiring harness between key reminder switch connector C-213 (terminal No. 12, 9, 11) and the KOS-ECU connector C-31 (terminal No. 4, 5, 31) in good condition? 

   1. YES:  Go to Step 4.
   2. NO:  The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
4. STEP 4. Replace the key reminder switch, and check whether the diagnostic trouble code is reset. 
   1. Erase the DTC.
   2. Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
   3. Check if the DTC is set.

   Q: Is the DTC set? 

   1. YES:  Replace KOS-ECU and register the ID codes (Refer to ID registration procedure manual - ID codes registration judgement table).
   2. NO:  The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).