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