Inspection Procedure 10: The auto light function does not work normally: Diagnosis

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 (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 R 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? 

   1. YES:  Go to Step 2.
   2. NO:  Repair the CAN bus line (Refer to DIAGNOSIS ).
      Fig 1: Identifying Special Tools

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

   Check if DTC is set to the LIN.

   Q: Is the DTC set? 

   1. YES:  Refer to DTC CHART  .
   2. NO:  Go to Step 3.
3. STEP 3. Using scan tool MB991958, read the ETACS diagnostic trouble code. 

   Check if DTC is set to the ETACS-ECU.

   Q: Is the DTC set? 

   1. YES:  Troubleshoot the ETACS (Refer to DIAGNOSTIC TROUBLE CODE CHART ).
   2. NO:  Go to Step 4.
4. STEP 4. Check that the headlights operate. 

   Check that the headlights (low-beam) illuminate normally.

   Q: Is the check result normal? 

   1. YES:  Go to Step 5.
   2. NO:  Refer to INSPECTION PROCEDURE 1 "NONE OF HEADLIGHTS (LOW-BEAM) ILLUMINATES."  .
5. STEP 5. Using scan tool MB991958, check data list 

   Use the ETACS-ECU service data to check the signals related to the operation of auto light function.

   • Turn the lighting switch to the "AUTO" position.

     Item No.	Item name	Normal condition
     Item 348	Headlight switch (auto)	ON

   Q: Do scan tool MB991958 display the items "Headlight switch (auto)" as normal condition? 

   1. YES:  Go to Step 6.
   2. NO:  Troubleshoot the ETACS-ECU. Refer to DIAGNOSIS .
6. STEP 6. Lighting control sensor check 

   Check the lighting control sensor. Refer to LIGHTING CONTROL SENSOR (LIGHT SENSOR) CHECK  .

   Q: Is the check result normal? 

   1. YES:  Go to Step 7.
   2. NO:  Replace the lighting control sensor.
7. STEP 7. Retest the system 

   Check that the auto light function works normally.

   Q: Is the check result normal? 

   1. YES:  The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
   2. NO:  Replace the ETACS-ECU.