Headlight Beam Level Control ECU Power Source Circuit: Wiring Diagram

WARNING: This page is about a different car, the 2006 Lexus GS 430 and 2006 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Headlight Beam Level Control ECU Power Source Circuit - Wiring Diagram

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INSPECT FUSE (H-LP LVL)
1. Remove the H-LP LVL fuse from the cowl side junction block RH.
2. Measure the resistance of the fuse.
  Standard resistance: Below 1 Ω
  
  NG : REPLACE FUSE
  
  OK : GO TO NEXT STEP

CHECK WIRE HARNESS (HEADLIGHT BEAM LEVEL CONTROL ECU - BATTERY AND BODY GROUND)

Disconnect the A43 ECU connector.

Measure the voltage and resistance of the wire harness side connector.

Standard voltage

STANDARD VOLTAGE SPECIFICATION

Tester Connection	Condition	Specified Condition
A43-14 (IG) - A43-1 (E1)	Engine switch on (IG)	10 to 14 V

Standard resistance

STANDARD RESISTANCE SPECIFICATION

Tester Connection	Specified Condition
A43-1 (E1) - Body ground	Below 1 Ω

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR

Fig 2: Identifying A43 ECU Connector

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