Lighting System Headlight Signal Circuit

Body Electrical. Lexus Is250, Is220D. Gse20 Ale20
Lighting. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH ASSEMBLY)

CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH)

CHECK HARNESS AND CONNECTOR (COMBINATION SWITCH ASSEMBLY - BODY GROUND)

CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH)

LIGHTING SYSTEM - Headlight Signal Circuit


DESCRIPTION

The main body ECU RH receives a HEAD position signal from the combination switch as a backup link. It also receives a signal from the combination switch via the multiplex communication system.
If this link is grounded, the headlights will illuminate.

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.Lighting.Lighting System.Lighting System Headlight Signal Circuit


INSPECTION PROCEDURE

1.CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH ASSEMBLY)


    Lexus Is250, Is220D. Gse20 Ale20.Lighting.Lighting System.Lighting System Headlight Signal Circuit

  1. Disconnect the J26 combination switch connector.

  1. Measure the voltage according to the value(s) in the table below.

    Standard voltage:
    Tester Connection
    		Condition
    		Specified Condition
    J26-4 (HEAD) - Body ground
    		Always
    		10 to 14 V


NG
Go to step 4
OK


2.CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH)


    Lexus Is250, Is220D. Gse20 Ale20.Lighting.Lighting System.Lighting System Headlight Signal Circuit

  1. Connect the J26 combination switch connector.

  1. Measure the voltage according to the value(s) in the table below.

    Standard voltage:
    Tester Connection
    		Condition
    		Specified Condition
    J26-4 (HEAD) - Body ground
    		Light control switch is off
    		10 to 14 V
    J26-4 (HEAD) - Body ground
    		Light control switch is in HEAD position
    		Below 1 V


NG
Go to step 3
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

3.CHECK HARNESS AND CONNECTOR (COMBINATION SWITCH ASSEMBLY - BODY GROUND)


    Lexus Is250, Is220D. Gse20 Ale20.Lighting.Lighting System.Lighting System Headlight Signal Circuit

  1. Disconnect the J26 combination switch connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    J26-5 (E) - Body ground
    		Always
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE WINDSHIELD WIPER SWITCH ASSEMBLY

4.CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH)


    Lexus Is250, Is220D. Gse20 Ale20.Lighting.Lighting System.Lighting System Headlight Signal Circuit

  1. Disconnect the J74 ECU connector.

  1. Disconnect the J26 combination switch connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    J74-23 (HEAD) - J26-4 (HEAD)
    		Always
    		Below 1 Ω
    J74-23 (HEAD) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE MAIN BODY ECU RH (COWL SIDE J/B RH)