Headlight Relay Circuit

Total OBD & ECU Auto Diagnostics

Total OBD & ECU Auto Diagnostics

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DESCRIPTION

The front controller controls the HEAD relay when a signal is received from the headlight dimmer switch assembly.

WIRING DIAGRAM

A3 Headlight (LH Low)

A39 Headlight (RH Low)

MAIN

MAIN

HEAD LH LWR

HEAD RH LWR

HEAD Relay

Engine Room J/B (Front Controller)

A4 Headlight Control ECU (LH)

,FL MAIN

A51 J/C

Battery

A26 Headlight Control ECU (RH)

A53 J/C

*1: with Smart Key System *2: without Smart Key System *3: HID Type *4: Except HID Type

E126255E02

INSPECTION PROCEDURE

PERFORM ACTIVE TEST BY INTELLIGENT TESTER

BODY NO. 5 (FRONT CONTROLLER):

(a) Connect the intelligent tester to the DLC3.

(b) Turn the ignition switch on (IG) and turn the intelligent tester main switch on.

(c) Select the item below in the ACTIVE TEST and then check the relay operation.

BODY NO. 5 (FRONT CONTROLLER):

Item

Test Details

Diagnostic Note

HEAD LIGHT (LO)

Light head (low) ON / OFF

-

Headlights come on.

Go to step 2

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

INSPECT RELAY

1

x

o

5

2

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

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

Standard resistance

Tester Connection

Specified Condition

3 - 5

10 kQ or higher

3 - 5

Below 1 Q (When battery voltage is applied to terminal 1 - 2)

REPLACE RELAY

REPLACE RELAY

CHECK HARNESS AND CONNECTOR (BATTERY - FRONT CONTROLLER)

(a) Disconnect the 1H connector from the front controller.

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

Croquis Camniones Asientos
Standard resistance

Tester Connection

Condition

Specified Condition

1H-3 - Body ground

Always

10 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (HEAD RELAY - BODY GROUND)

(a) Using a service wire, connect the 1H-3 on the wire harness side and body ground. OK:

Headlight comes on.

E125617E12

REPAIR OR REPLACE HARNESS OR CONNECTOR

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

Headlight (HI-BEAM) Circuit

DESCRIPTION

The front controller receives headlight HI switch information from the combination switch, and turns on the headlights.

WIRING DIAGRAM

Engine Room J/B (Front Controller)

Engine Room J/B (Front Controller)

Toyota Yaris Smart Key System

INSPECTION PROCEDURE

PERFORM ACTIVE TEST BY INTELLIGENT TESTER

(a) Connect the intelligent tester to the DLC3.

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Responses

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