Inspection Procedure 1: The Diagnosis Code is not Set.
caution
Before replacing the ECU, 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 have a problem.
PROBABLE CAUSES
Malfunction of the headlamp automatic levelling ECU
STEP 2. Resistance measurement at the C-112 headlamp automatic levelling ECU connector.
(1)Disconnect the connector, and measure the resistance at the wiring harness-side connector.
(2)Measure the resistance between the C-112 headlamp automatic levelling ECU connector terminal No. 14 and the 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. Wiring harness check between the C-112 headlamp automatic levelling ECU connector terminal No. 14 and the body earth
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 the C-112 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 the C-112 headlamp automatic levelling ECU connector terminal No. 1 and the body earth OK: Battery voltage
Q.
Is the check result normal?
Go to Step 6.
Go to Step 5.
STEP 5. Wiring harness check between the C-112 headlamp automatic levelling ECU connector terminal No. 1 and the fusible link (33)
note
Before the wiring harness check, check the ETACS-ECU connectors C-309 and C-317, and the intermittent connector C-37. Then, repair them if necessary.
Check the power supply line for open or short circuit.
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Go to Step 2.
Repair the defective connector.
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