DTC B2409 STL unit comm.(No response): Diagnosis

WARNING: This page is about a different car, the 2008 Mitsubishi Lancer. However, it is still accessible from the selected car via links, so may be relevant.

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

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?

YES : Go to Step 2.

NO : Repair the CAN bus line. (Refer to DIAGNOSIS ).
STEP 2. Check key reminder switch connector C-211 and KOS-ECU connector C-05 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is the key reminder switch connector C-211 and KOS-ECU connector C-05 in good condition?

YES : Go to Step 3.

NO : Repair the defective connector.
STEP 3. Wiring harness check between C-211 key reminder switch connector and C-05 KOS-ECU connector for open circuit.
1. Disconnect C-211 key reminder switch connector and C-05 KOS-ECU connector.
2. Measure at the connector side of C-211 key reminder switch connector and C-05 KOS-ECU connector.
3. Measure the resistance between the terminals.
  - C-211 key reminder switch connector terminal No.9 - C-05 KOS-ECU connector terminal No.5.
    
    Fig 2: Checking Resistance Between Connector Terminal 9 And 5
    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  - C-211 key reminder switch connector terminal No.11 - C-05 KOS-ECU connector terminal No.31.
    
    Fig 3: Checking Resistance Between Connector Terminal 11 And 31
    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  - C-211 key reminder switch connector terminal No.12 - C-05 KOS-ECU connector terminal No.4.
    OK: Continuity exists (2Ω or less)
    
    Fig 4: Checking Resistance Between Connector Terminal 12 And 4
    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Q: Is the check result normal?

YES : Go to Step 4.

NO (C-211 key reminder switch connector terminal No.9 - C-05 KOS-ECU connector terminal No.5.) : An open circuit is present in the wiring harness between C-211 key reminder switch connector terminal No. 9 and C-05 KOS-ECU connector terminal No. 5. Repair the wiring harness.

NO (C-211 key reminder switch connector terminal No.11 - C-05 KOS-ECU connector terminal No.31.) : An open circuit is present in the wiring harness between C-211 key reminder switch connector terminal No. 11 and C-05 KOS-ECU connector terminal No. 31. Repair the wiring harness.

NO (C-211 key reminder switch connector terminal No.12 - C-05 KOS-ECU connector terminal No.4.) : An open circuit is present in the wiring harness between C-211 key reminder switch connector terminal No. 12 and C-05 KOS-ECU connector terminal No. 4. Repair the wiring harness.
STEP 4. Check the wiring harness between the C-211 key reminder switch connector (terminal Nos. 9, 11, 12) and the ground for short circuit.
1. Disconnect C-211 key reminder switch connector, and check the wiring harness.
2. Check the wiring harness between C-211 key reminder switch connector (terminal No.9) and ground
  OK: No Continuity
  
  Fig 5: Checking Wiring Harness Between C-211 Key Reminder Switch Connector Terminal 9 And Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Check the wiring harness between C-211 key reminder switch connector (terminal No.11) and ground
  OK: No Continuity
  
  Fig 6: Checking Wiring Harness Between C-211 Key Reminder Switch Connector Terminal 11 And Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
4. Check the wiring harness between C-211 key reminder switch connector (terminal No.12) and ground
  OK: No Continuity
  
  Fig 7: Checking Wiring Harness Between C-211 Key Reminder Switch Connector Terminal 12 And Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Q: Is the wiring harness between C-211 key reminder switch connector (terminal No. 9, 11, 12) and the ground in good condition?

YES : Go to Step 5.

NO (key reminder switch connector C-211 terminal No.9 - ground.) : Repair the wiring harness between C-211 key reminder switch connector (terminal No. 9) and the ground.

NO (key reminder switch connector C-211 terminal No.11 - ground.) : Repair the wiring harness between C-211 key reminder switch connector (terminal No. 11) and the ground.

NO (key reminder switch connector C-211 terminal No.12 - ground.) : Repair the wiring harness C-211 key reminder switch connector (terminal No. 12) and the ground.
STEP 5. 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?

YES : Replace KOS-ECU and register the ID codes (Refer to ID CODE REGISTRATION NECESSITY JUDGMENT TABLE ).

NO : The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).