Inspection Procedure
3: One of the automatic levellings does not work.
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Before replacing the ECU,
ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
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COMMENTS ON TROUBLE SYMPTOM
When one of the automatic levellings does not work, the wiring harness and connector(s)
between the headlamp automatic levelling-ECU and the headlamp levelling unit, or the headlamp
assembly (headlamp levelling unit) may have a problem.
PROBABLE CAUSES
- Malfunction of headlamp assembly (headlamp levelling
unit)
- Malfunction of headlamp automatic levelling-ECU
- Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. Headlamp levelling unit check.
Perform a levelling motor drive test of the headlamp levelling unit to check that the
motor is driven. Refer to 
.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
NO (The left levelling motor is not driven.)
: Go to Step 2.
NO (The right levelling motor is not driven.) : Go to Step 5.
STEP 2. Check of open circuit in MB, MS and MG line between the headlamp
automatic levelling-ECU connector and the headlamp assembly (LH) connector.
Q.
Is the check result normal?
Repair the connector(s) or wiring harness.
STEP 3. M.U.T.-III data list.
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(1)Disconnect the headlamp assembly (LH) and (RH) connector.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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Item No.
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Item name
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Normal condition
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68
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Actuator output voltage
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Indicates the voltage value of system voltage within the range of
20 to 80%.
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OK: Normal condition is displayed.
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Q.
Is the check result normal?
Go to Step 4.
Replace the headlamp automatic levelling-ECU (Refer to ).
STEP 4. Check the headlamp assembly (LH).
Check the headlamp assembly (LH) for internal failure.
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(1)Disconnect the headlamp assembly (RH) connector.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Perform the drive test using the M.U.T.-III. Refer to .
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Q.
Is the check result normal?
Go to Step 8.
Replace the headlamp assembly (LH) (Refer to ).
STEP 5. Check of open circuit in MB, MS and MG line between the headlamp
automatic levelling-ECU connector and the headlamp assembly (RH) connector.
Q.
Is the check result normal?
Repair the connector(s) or wiring harness.
STEP 6. M.U.T.-III data list.
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(1)Disconnect the headlamp assembly (LH) and (RH) connector.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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Item No.
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Item name
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Normal condition
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68
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Actuator output voltage
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Indicates the voltage value of system voltage within the range of
20 to 80%.
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OK: Normal condition is displayed.
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Q.
Is the check result normal?
Go to Step 7.
Replace the headlamp automatic levelling-ECU (Refer to ).
STEP 7. Check the headlamp assembly (RH).
Check the headlamp assembly (RH) for internal failure.
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(1)Disconnect the headlamp assembly (LH) connector.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)Perform the drive test using the M.U.T.-III. Refer to .
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Q.
Is the check result normal?
Go to Step 8.
Replace the headlamp assembly (RH) (Refer to ).
STEP 8. Retest the system.
Check that the automatic levelling of the right headlamp operates normally.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the headlamp automatic levelling-ECU (Refer to ).