Headlight Relay Circuit: Procedure

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

PERFORM ACTIVE TEST USING TECHSTREAM

Connect the Techstream to the DLC3.
Turn the ignition switch on (IG).
Turn the Techstream on.
Enter the following menus: Body Electrical / Body No. 5 / Active Test.

Check the operation.

BODY NO. 5 (FRONT CONTROLLER)

Tester Display	Test Part	Control Range	Diagnostic Note
Light Head (Low)	Headlight (Low)	ON/OFF	-

Headlights come on.

NG → See step 2

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

INSPECT RELAY

Remove the HEAD relay from the engine room R/B & J/B.

Fig 1: Identifying Headlight Relay Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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 terminal 1 - 2)

NG → REPLACE RELAY

OK: Go to next step

CHECK HARNESS AND CONNECTOR (BATTERY - FRONT CONTROLLER)

Disconnect the 1H connector from the front controller.

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

Fig 2: Identifying Front Controller Connector Terminals

Standard voltage

Tester Connection	Condition	Specified Condition
1H-3 - Body ground	Always	10 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step

CHECK HARNESS AND CONNECTOR (HEAD RELAY - BODY GROUND)
1. Using a service wire, connect the 1H-3 on the wire harness side and body ground.
  OK
  
  Headlight comes on.
  
  Fig 3: Identifying Front Controller (1H) Connector Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

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