Inspection Procedure 10: The auto lamp function does not work normally.

caution

Whenever the ECU is replaced, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.

OPERATION

The ETACS-ECU operates this function in accordance with the vehicle speed signal and the input signals from the lighting control sensor and column switch (lighting switch). When the lighting switch is in the AUTO position, and when an abnormality is present to the lighting control sensor circuit, the fail-safe function is activated and the low beam is turned ON at all times regardless of the brightness around the vehicle. In addition, the customisation items about M.U.T.-III auto lamp function will disappear.

COMMENTS ON TROUBLE SYMPTOM

If the auto lamp function does not work normally, the above input signal circuit(s) or the ETACS-ECU may have a problem.

PROBABLE CAUSES

Malfunction of the lighting control sensor
Malfunction of the lighting switch
Malfunction of the ETACS-ECU
Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

Use the 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

STEP 2. M.U.T.-III diagnosis code

Check if diagnosis code is set to the ASC-ECU.

Q. Is the diagnosis code set?

Diagnose the ASC-ECU. (Refer to GROUP 35C - Troubleshooting

Go to Step 3.

STEP 3. Check that the headlamps operate.

Check that the low beam and high beam headlamps illuminate normally.

Q. Is the check result normal?

Go to Step 4

Repair the headlamps.

STEP 4. M.U.T.-III data list

Check the ETACS-ECU signals, which are related to the auto lamp function.

Move the electric motor switch to the ON position.

Item No.	Item name	Normal condition
30	IG SW (IG1) /Power SW(ON)	ON

OK: Normal condition is displayed.

Q. Is the check result normal?

Go to Step 5.

Refer to inspection procedure 2 "The electric motor switch (IG1) signal is not received

STEP 5. Connector check: B-07 lighting control sensor connector, B-318 ETACS-ECU connector

Q. Is the check result normal?

Go to Step 6.

Repair the defective connector.

STEP 6. Check the wiring harness between B-07 lighting control sensor connector terminal No.1, 2, 3 and the B-318 ETACS-ECU connector terminal No.29, 28, 37.

Check the power supply lines, earth lines, and output lines for open circuit and short circuit.

Q. Is the check result normal?

Go to Step 7.

Repair the wiring harness.

STEP 7. Retest the system

Substitute the lighting control sensor with good one temporarily, and check that the auto lamp function operates normally.

Q. Is the check result normal?

Replace the lighting control sensor.

Go to Step 8.

STEP 8. Retest the system

Substitute the lighting switch with good one temporarily, and check that the auto lamp function operates normally.

Q. Is the check result normal?

Replace the lighting switch.

Replace the ETACS-ECU and register the ID codes (Refer to

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