Inspection Procedure 2: The headlamps 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 lamps of a preceding vehicle or oncoming vehicle). Prior to the diagnosis, see "General information" . Grasp the details if necessary.
  • Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.

COMMENTS ON TROUBLE SYMPTOM


When the headlamps 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), unfavourable 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.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE


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.

Q. 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.


Q. 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 .

Q. 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.

Q. Is the check result normal?

An external factor affected the system (Refer to "General information" ).

Replace the FCM/LDW/AHB-ECU (Refer to ).