Inspection Procedure 2: The LDW does not enter the warning monitor mode under some circumstances.

caution

The system may not also work correctly under certain external factors (such as weather, road conditions, or ambient environments). Prior to the diagnosis, 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 LDW does not enter the warning monitor mode, 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 (scratches, contamination, icing, fog on the windshield or the sensor), or a faulty FCM/LDW/AHB-ECU.

note

The system does not proceed to the warning monitor mode when any of the followings is satisfied:

Narrow road (width: less than 2.5 mm)
The road where white and yellow lines intersect
The road where the distances among two white and one yellow lines are narrow
The road where the distances among one white and two yellow lines are narrow

PROBABLE CAUSES

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: lane improperly detected)

DIAGNOSIS PROCEDURE

STEP 1. Check the sensor 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. M.U.T.-III data list

Check the FCM/LDW/AHB-ECU data list (Refer to

The vehicle is being driven on the road where lane division lines are clear with the LDW activated.

Item No.	Item name	Normal condition
Item 41	LDW lane detection (RH)	ON
Item 42	LDW lane detection (LH)	ON

The vehicle is being driven on the road where lane division lines are not clear with the LDW activated.

Item No.	Item name	Normal condition
Item 41	LDW lane detection (RH)	OFF
Item 42	LDW lane detection (LH)	OFF

OK: Normal condition is displayed.

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 LDW operates normally.

Q. Is the check result normal?

This symptom is caused by a bad weather or road conditions. It is not a malfunction.

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