Toyota 4Runner: Headlight Relay Circuit

Toyota 4Runner Service Manual / Vehicle Exterior / Lighting (ext) / Lighting System / Headlight Relay Circuit

DESCRIPTION

The main body ECU receives headlight dimmer switch information signals, and illuminates the low beam headlight.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses and bulbs for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	PERFORM ACTIVE TEST USING TECHSTREAM (HEADLIGHT RELAY)

(a) Using the Techstream, perform the Active Test (See page ).

Main Body

Tester Display	Test Part	Control Range	Diagnostic Note
Headlight Relay	Low beam headlight relay	ON/OFF	-

OK:

Headlight relay operates (low beam headlights illuminate).

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	INSPECT HEADLIGHT RELAY (H-LP LO)

(a) Remove the headlight relay from the engine room relay block, junction block.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
3 - 5	Battery voltage not applied between terminals 1 and 2	10 kΩ or higher
3 - 5	Battery voltage applied between terminals 1 and 2	Below 1 Ω

REPLACE HEADLIGHT RELAY

3.	CHECK HARNESS AND CONNECTOR (BATTERY - HEADLIGHT RELAY [H-LP LO])

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
Headlight relay terminal 1 - Body ground	Always	11 to 14 V
Headlight relay terminal 5 - Body ground	Always	11 to 14 V

Text in Illustration

*a	Front view of wire harness connector (to Headlight Relay)

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY [H-LP LO] - MAIN BODY ECU)

(a) Remove the main body ECU (See page ).

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
Headlight relay terminal 2 - A-15 (HRLY)	Always	Below 1 Ω
A-15 (HRLY) - Body ground	Always	10 kΩ or higher

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPAIR OR REPLACE HARNESS OR CONNECTOR

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