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 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.