DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
PERFORM ACTIVE TEST BY INTELLIGENT TESTER
INSPECT FUSE (H-LP L LWR, H-LP R LWR)
INSPECT HEAD LP RELAY
CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - BATTERY)
CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - BATTERY AND BODY GROUND)
CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - HEAD LP RELAY)
LIGHTING SYSTEM - Headlight Relay Circuit
DESCRIPTION
The headlight relay is turned on by operating the headlight switch.
When the theft deterrent system is activated, it causes the ECU to turn the headlight relay on and off repeatedly at approximately 0.25 second intervals to flash the headlights.
In this condition, if any of the following operations is performed, the ECU turns the headlight relay off to stop the headlight from flashing:
Unlock the driver door with a key.
Turn the engine switch on (ACC or IG).
Unlock the doors with the wireless door lock control system.
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.PERFORM ACTIVE TEST BY INTELLIGENT TESTER |
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the intelligent tester main switch on.
Select the item below in the ACTIVE TEST and then check the relay operation.
ACTIVE TEST: Body (Main Body ECU RH)| Item | Test Details | Diagnostic Note |
| Headlight Relay | Headlight relay ON / OFF | - |
- OK:
- Headlight assembly (low) illuminates.
| | PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE |
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|
| 2.INSPECT FUSE (H-LP L LWR, H-LP R LWR) |
Remove the H-LP L LWR fuse from the engine room No. 2 relay block .
Remove the H-LP R LWR fuse from the engine room No. 2 relay block .
Measure the resistance of the fuses.
- Standard resistance:
- Below 1 Ω
Remove the HEAD LP relay from the engine room No. 1 relay block.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Specified Condition |
| 3 - 5 | 10 kΩ or higher |
| 3 - 5 | Below 1 Ω
(When battery voltage is applied to terminals 1 and 2) |
| 4.CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - BATTERY) |
Disconnect the RL main body ECU RH connector.
Measure the voltage according to the value(s) in the table below.
- Standard voltage:
| Tester Connection | Condition | Specified Condition |
| RL-7 (HRLY) - Body ground | Always | 10 to 14 V |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| 5.CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - BATTERY AND BODY GROUND) |
Check the wire harness between the headlight (Low LH) and battery, and the headlight (Low LH) and body ground.
Disconnect the B12 headlight connector.
Measure the voltage and resistance according to the value(s) in the table below.
- Standard voltage:
| Tester Connection | Condition | Specified Condition |
| B12-17 (LO) - Body ground | Turn the light control switch to the ON (HEAD) position. | 10 to 14 V |
- Standard resistance:
| Tester Connection | Condition | Specified Condition |
| B12-16 (E) - Body ground | Always | Below 1 Ω |
Check the wire harness between the headlight (Low RH) and battery, and the headlight (Low RH) and body ground.
Disconnect the B2 headlight connector.
Measure the voltage and resistance according to the value(s) in the table below.
- Standard voltage:
| Tester Connection | Condition | Specified Condition |
| B2-17 (LO) - Body ground | Turn the light control switch to the ON (HEAD) position. | 10 to 14 V |
- Standard resistance:
| Tester Connection | Condition | Specified Condition |
| B2-16 (E) - Body ground | Always | Below 1 Ω |
| | REPLACE HEADLIGHT ASSEMBLY (LOW LH OR LOW RH) |
|
|
| 6.CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - HEAD LP RELAY) |
Check the harness and the connectors between the headlight (Low LH or Low RH) and the HEAD LP relay.
Disconnect the B12 light connector.
Remove the HEAD LP relay from the engine room No. 1 relay block.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
- Check for open:
| Headlight Assembly | Tester Connection | Specified Condition |
| LH | B12-17 (LO) - HEAD LP relay terminal (3) | Below 1 Ω |
| RH | B2-17 (LO) - HEAD LP relay terminal (3) | Below 1 Ω |
- Check for short:
| Headlight Assembly | Tester Connection | Specified Condition |
| LH | B12-17 (LO) or HEAD LP relay terminal (3) - Body ground | 10 kΩor higher |
| RH | B2-17 (LO) or HEAD LP relay terminal (3) - Body ground | 10 kΩor higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| OK | |
| |
| REPLACE MAIN BODY ECU RH (COWL SIDE J/B RH) |
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LEXUS IS250, IS220d / GSE20 ALE20
