Toyota 4Runner manuals

Toyota 4Runner: 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).


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


NG

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

Battery voltage applied between terminals 1 and 2

Below 1 Ω


NG

REPLACE HEADLIGHT RELAY


OK

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

Text in Illustration

*a

Front view of wire harness connector

(to Headlight Relay)



NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

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


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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