Toyota Tundra Service Manual: Front Fog Light Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives headlight dimmer switch assembly (front fog light switch) information signals and illuminates the front fog lights.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM

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

Click here

Main Body

Tester Display

Test Part

Control Range

Diagnostic Note

Front Fog Light Relay

Front fog light relay (FOG FR)

OFF or ON

-

OK:

Front fog light relay (FOG FR) operates (front fog lights turn on).

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

INSPECT FRONT FOG LIGHT RELAY (FOG FR)

(a) Remove the front fog light relay (FOG FR) from the engine room relay block and junction block.

(b) Inscpect the front fog light relay (FOG FR).

Click here

NG

REPLACE FRONT FOG LIGHT RELAY (FOG FR)

OK

3.

CHECK HARNESS AND CONNECTOR (FRONT FOG LIGHT CIRCUIT)

(a) Remove the front fog light relay (FOG FR) from the engine room relay block and junction block.

(b) Disconnect the 3H driver side junction block assembly connector.

(c) Disconnect the A30 fog light assembly LH connector.

(d) Disconnect the A31 fog light assembly RH connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

Front fog light relay (FOG FR) terminal 1 - Body ground

Light control switch tail position

11 to 14 V

Front fog light relay (FOG FR) terminal 3 - Body ground

Always

11 to 14 V

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Front fog light relay (FOG FR) terminal 2 - 3H-25

Always

Below 1 Ω

Front fog light relay (FOG FR) terminal 5 - A30-2

Always

Below 1 Ω

Front fog light relay (FOG FR) terminal 2 or 3H-25 - Body ground

Always

10 kΩ or higher

Front fog light relay (FOG FR) terminal 5 or A30-2 - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

CHECK DRIVER SIDE JUNCTION BLOCK ASSEMBLY

(a) Remove the driver side junction block assembly.

Click here

*a

Component without harness connected

(Driver Side Junction Block Assembly)

(b) Remove the main body ECU (multiplex network body ECU) from the driver side junction block assembly.

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3H-25 - A-7 (FFGO)

Always

Below 1 Ω

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY

    Dtc Check / Clear

    Hazard Warning Switch Circuit

    See More:

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