DTC U0231: Lighting control sensor LIN timeout < Vehicles with auto light function >: 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. Check ETACS-ECU connectors C-316 and C-317 and lighting control sensor connector D-39 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are ETACS-ECU connectors C-316 and C-317 and lighting control sensor connector D-39 in good condition? 

   • YES:  Go to Step 2.
   • NO:  Repair or replace the damaged component(s). Go to Step  7.
2. STEP 2. Check the ground circuit to the lighting control sensor. Measure the resistance at lighting control sensor connector D-39. 
   1. Disconnect power window main switch connector D-39 and measure the resistance available at the wiring harness side of the connector.
   2. Measure the resistance value between power window main switch connector D-39 terminal 2 and ground.
      • The resistance should be 2 ohms or less.

      Q: Is the measured resistance 2 ohms or less? 

      • YES:  Go to Step  4.
      • NO:  Go to Step 3.
        Fig 1: Measuring Resistance Between Power Window Main Switch Connector D-39 Terminal 2 And Ground

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. STEP 3. Check the wiring harness between lighting control sensor connector D-39 (terminal 2) and the ground. 
   • Check the ground wires for open circuit.

     Q: Is the wiring harness between lighting control sensor connector D-39 (terminal 2) and the ground in good condition? 

     • YES:  No action is necessary and testing is complete.
     • 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. Check the battery power supply circuit to the lighting control sensor. Measure the voltage at lighting control sensor connector D-39. 
   1. Disconnect lighting control sensor connector D-39 measure the voltage available at the wiring harness side of the connector.
   2. Measure the voltage between lighting control sensor connector D-39 terminal 2 and ground.
      • The voltage should measure approximately 12 volts (battery positive voltage).

      Q: Is the measured voltage approximately 12 volts (battery positive voltage)? 

      • YES:  Go to Step  6.
      • NO:  Go to Step 5.
        Fig 2: Measuring Voltage Between Power Window Main Switch Connector D-39 Terminal 2 And Ground

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. STEP 5. Check the wiring harness between ETACS-ECU connector C-317 (terminal 10) and lighting control sensor connector D-39 (terminal 1). 
   • Check the power supply line (battery supply) for open circuit and short circuit.

     Q: Is the wiring harness between ETACS-ECU connector C-317 (terminal 10) and lighting control sensor connector D-39 (terminal 1) in good condition? 

     • YES:  No action is necessary and testing is complete.
     • 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.
6. STEP 6. Check the wiring harness between ETACS-ECU connector C-316 (terminal 1) and lighting control sensor connector D-39 (terminal 3). 
   • Check the communication line for open circuit.

     Q: Is the wiring harness between ETACS-ECU connector C-316 (terminal 1) and lighting control sensor connector D-39 (terminal 3) in good condition? 

     • YES:  Go to Step 7.
     • 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. Go to Step 7.
7. STEP 7. Recheck for diagnostic trouble code. 

   Check again if the DTC is set to the ETACS-ECU.

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

      Q: Is the DTC set? 

      • YES:  Replace the lighting control sensor.
      • NO:  A poor connection, open circuit or other intermittent malfunction is present in the LIN bus lines between the lighting control sensor and the ETACS-ECU (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .
        Fig 3: Connecting Scan Tool To Data Link Connector

        Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.