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Inspection Procedure 2: The headlights cannot be switched from low-beam to high-beam and vice versa on an automatic basis frequently.
 
 
caution
  • The system may not also work correctly under certain external factors (such as weather, road conditions, environments, the exterior lights of a preceding vehicle or oncoming vehicle). Prior to the diagnosis, refer to trouble symptom chart . Grasp the details if necessary.
  • Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
COMMENTS ON TROUBLE SYMPTOM
When the headlights cannot be switched from low beam to high beam and vice versa on an automatic basis frequently, any of the followings are suspected: bad weather (heavy rain, snow, icing), unfavorable road condition, ambient environment, blocked FCM/LDW/AHB-ECU sensor or its surroundings (cracks, contamination, icing, fog on the windshield or the sensor), a faulty FCM/LDW/AHB-ECU.
 
 
TROUBLESHOOTING HINTS
  • Faults on the windshield glass (such as scratch, cracks, contamination or drain drops on the glass surface)
  • FCM/LDW/AHB-ECU improperly installed
  • Faulty FCM/LDW/AHB-ECU (sensor: poor illumination)
 
 
DIAGNOSIS
STEP 1. Check the FCM/LDW/AHB-ECU mounted surface on the windshield.
Visually check the FCM/LDW/AHB-ECU mounted surface on the windshield for scratch, cracks, contamination or drain drops.
Is the check result normal?
Go to Step 2.
Windshield glass replacement (Refer to GROUP 42A - Windshield Glass Removal and Installation ).
 
STEP 2. Check whether the FCM/LDW/AHB-ECU is installed properly.
Is the check result normal?
Go to Step 3.
Install the FCM/LDW/AHB-ECU properly.
 
STEP 3. Operation check of the automatic high beam system.
Refer to .
Is the check result normal?
Go to Step 4.
Replace the FCM/LDW/AHB-ECU (Refer to ).
 
STEP 4. Retest the system.
Check that the automatic high beam operates normally.
Is the check result normal?
An external factor affected the system (Refer to trouble symptom chart ).
Replace the FCM/LDW/AHB-ECU (Refer to ).