Before replacing
the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit
are normal.
DIAGNOSTIC FUNCTION
When the LDW-ECU receives the signal which indicates that a neutral position has not been
learned via CAN communication with the steering wheel sensor, diagnosis code No. B2507 will
be stored.
JUDGEMENT CRITERIA
When the LDW-ECU receives the signal which indicates that a neutral position has not been
learned via CAN communication with the steering wheel sensor, it will determines that the system
is defective.
PROBABLE CAUSES
Neutral position of steering wheel sensor not learned
Steering wheel sensor malfunction
Malfunction of the LDW-ECU
Malfunction of the CAN bus line.
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
On completion, go to Step 2.
STEP 2. M.U.T.-III other system diagnosis code
Check if diagnosis code is set to the ASC-ECU
Q.
Is the diagnosis code set?
Troubleshoot the ASC. Refer to GROUP 35C - Troubleshooting .
Go to Step 3
STEP 3. Check whether the diagnosis code is reset.
Follow the procedure below to check whether the LDW-ECU stores diagnosis code No. B2507.
(1)Perform calibration of steering wheel sensor (Refer to ).
(2)Erase the diagnosis code.
(3)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(4)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Go to Step 4
The diagnosis is complete.
STEP 4. M.U.T.-III data list
Check the LDW-ECU service data.
When the steering wheel sensor neutral point is learned.
Item No.
Item name
Normal condition
Item 12
Steering angle sensor status
Normal
Vehicle stopped (the steering wheel is in the neutral
position)
Item No.
Item name
Normal condition
Item 13
Steering angle
-6 to 6 deg
Running
Item No.
Item name
Normal condition
Item 13
Steering angle
Nearly the same as the steering wheel operation angle <-720
to 720 deg (LDW-ECU normal detection value)>
OK: Normal conditions are displayed for all the items.
Q.
Is the check result normal?
Go to Step 5
Replace the steering wheel sensor.
STEP 5. Check whether the diagnosis code is reset.
Check if the diagnosis code No. B2507 is set to LDW-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the LDW-ECU.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
).
On completion, go to Step 2.