Inspection Procedure 2: Neither Right nor Left Automatic Levelling Operates.


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
















OPERATION
When a vehicle is at a standstill or being driven at a constant speed for 12 seconds or more (except on rough road), the headlamp automatic levelling-ECU inputs a headlamp LO relay signal, vehicle speed signal, and height signal for judgment and operates the levelling.
note The automatic levelling during driving at a constant speed operates only once after starting driving. The automatic levelling does not work if the vehicle pitch angle during driving at a constant speed and the vehicle pitch angle when the vehicle is stopped are the same.

COMMENTS ON TROUBLE SYMPTOM
Assuming that the automatic levelling diagnosis code is not set, if neither right nor left automatic levelling operates, the headlamp automatic levelling-ECU, wiring harness and connectors between the headlamp automatic levelling-ECU and the front-ECU (headlamp relay: LO), the vehicle speed sensor (vehicle signal abnormality), or wiring harness and connectors between the headlamp automatic levelling-ECU and the vehicle speed sensor may be defective.

PROBABLE CAUSES

  • Malfunction of the headlamp automatic levelling-ECU
  • Malfunction of the vehicle speed sensor
  • Damaged wiring harness and connectors

DIAGNOSIS PROCEDURE

STEP 1. Check the diagnosis code.

Q. Does the warning lamp blink normally?
Go to Step 2.
INSPECTION PROCEDURE 1 "Diagnosis code is not set." Refer to

STEP 2. Check the speed meter.

Q. Does the speed meter operate normally?
Go to Step 3.
Carry out troubleshooting for the speed meter. (Refer to Combination Meter - Troubleshooting .) After the troubleshooting for the speed meter, go to Step 3.

STEP 3. Connector check: D-125 Headlamp automatic levelling-ECU connector

Q. Is the check result normal?
Go to Step 4.
Repair the defective connector.

STEP 4. Voltage measurement at D-125 headlamp automatic levelling-ECU connector.
(1)Disconnect the connector, and measure at the wiring harness-side connector.
(2)Turn "ON" the headlamp switch.
(3)Voltage between D-125 headlamp automatic levelling-ECU connector (terminal No. 6) and body earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6.
Go to Step 5.

STEP 5. Check the wiring harness between D-125 headlamp automatic levelling-ECU connector (terminal No. 6) and A-08X front-ECU connector (terminal No. 6).
note Prior to the wiring harness inspection, check intermediate connector D-239, joint connector A-16, and repair if necessary.

  • Check the communication lines for open circuit and short circuit.

Q. Is the check result normal?
Go to Step 6.
Repair the wiring harness.

STEP 6. Connector check: C-16 vehicle speed sensor connector and D-125 headlamp automatic levelling-ECU connector

Q. Is the check result normal?
Go to Step 7.
Repair the defective connector.

STEP 7. Check the wiring harness between D-125 headlamp automatic levelling-ECU connector (terminal No. 9) and C-16 vehicle speed sensor connector (terminal No. 3).

  • Check the communication lines for open circuit.
note Prior to the wiring harness inspection, check intermediate connector D-228 and joint connector D-37, and repair if necessary.

Q. Is the check result normal?
Go to Step 8.
Repair the wiring harness.

STEP 8. Retest the system.
Check that the automatic levelling operates normally.

Q. Is the check result normal?
Intermittent malfunction. (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .)
Replace the headlamp automatic levelling-ECU.