Inspection Procedure 1: The Diagnosis Code is not Set.


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














COMMENTS ON TROUBLE SYMPTOM
If neither normal nor abnormal diagnosis code is set, the headlamp automatic levelling-ECU, the headlamp automatic levelling-ECU power supply, wiring harness or connectors of earth, or wiring harness and connectors between the headlamp automatic levelling-ECU and diagnosis connector may be defective.

PROBABLE CAUSES

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

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-125 Headlamp automatic levelling-ECU connector

Q. Is the check result normal?
Go to Step 2.
Repair the defective connector.

STEP 2. Measure the resistance at the D-125 headlamp automatic levelling-ECU connector.
(1)Disconnect the connector, and measure the resistance at the wiring harness-side connector.
(2)Measure the resistance between D-125 headlamp automatic levelling-ECU connector (terminal No. 14) and body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 4.
Go to Step 3.

STEP 3. Check the wiring harness between D-125 headlamp automatic levelling-ECU connector (terminal No.14) and body earth.
note Prior to the wiring harness inspection, check joint connector D-34, and repair if necessary.

  • Check the earth wires for open circuit.

Q. Is the check result normal?
Go to Step 4.
Repair the wiring harness.

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 the ignition switch to the "ON" position.
(3)Voltage between D-125 headlamp automatic levelling-ECU connector (terminal No. 1) 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.1) and ignition switch (IG1).

  • Check the power supply line for open circuit and short circuit.
note Prior to the wiring harness inspection, check junction block connector D-403 and D-405, and repair if necessary.

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

STEP 6. Connector check: D-127 Diagnosis connector

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

STEP 7. Check the wiring harness from D-125 headlamp automatic levelling-ECU connector (terminal No. 5 and 7) to D-127 diagnosis connector(terminal No. 1 and 10).

  • Check the communication lines for open circuit and short circuit.
note Prior to the wiring harness inspection, check joint connector D-34, and repair if necessary.

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

STEP 8. Retest the system.
Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Refer to diagnosis code chart .
Replace the headlamp automatic levelling-ECU.