Operation CHARM: Car repair manuals for everyone.
Home >> Lexus >> 2012 >> IS 250 AWD V6-2.5L (4GR-FSE) >> Repair and Diagnosis >> Lighting and Horns >> Testing and Inspection >> Component Tests and General Diagnostics >> Lighting System >> Headlight Signal Circuit
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Headlight Signal Circuit





LIGHTING: LIGHTING SYSTEM: Headlight Signal Circuit
- 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





INSPECTION PROCEDURE

PROCEDURE

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

(a) Disconnect the J26 combination switch connector.





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

Standard voltage:





NG -- CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - COMBINATION SWITCH)
OK -- Continue to next step.

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

(a) Connect the J26 combination switch connector.





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

Standard voltage:





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

OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

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

(a) Disconnect the J26 combination switch connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE WINDSHIELD WIPER SWITCH ASSEMBLY

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

(a) Disconnect the J74 ECU connector.





(b) Disconnect the J26 combination switch connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE MAIN BODY ECU RH (COWL SIDE J/B RH)
pro multis · About Operation CHARM