LIGHTING SYSTEM Front Fog Light Circuit

DTC Code DTC Name
Front Fog Light Circuit

DESCRIPTION

When both of the following conditions are met, the front fog lights come on.

  • The taillights are turned on by automatic light control or manual light control.

  • The front fog light switch is on.

When either of the following conditions is met, the front fog lights turn off.

  • The front fog light switch is off.

  • The taillights are off.

Tip:

  • This circuit is only for vehicles with automatic light control or daytime running light control.

  • If the vehicle has automatic light control or daytime running light control, the exterior lights (headlights, taillights, front fog lights and rear fog light) are controlled by the main body ECU.

  • If the vehicle does not have automatic light control or daytime running light control, the exterior lights (headlights, taillights, front fog lights and rear fog light) are not controlled by the main body ECU. Perform troubleshooting according to the Problem Symptoms Table (Click here).

  • Before performing troubleshooting of front fog light control, check that the taillights operate normally.

  • If a front fog light on only one side does not illuminate, inspect the bulb or wire harness that is related to the fog light.

  • If both the right and left front fog lights do not illuminate, perform the front fog light relay Active Test and read the front fog light switch value in the Data List to determine if the malfunction exists on either the switch side or the relay side.

WIRING DIAGRAM

E186277E04

CAUTION / NOTICE / HINT

Note:

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

PROCEDURE

  1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (FRONT FOG LIGHT RELAY)

    1. Using the intelligent tester, perform the Active Test (Click here).

      Table 1. Main Body

      Tester Display

      Test Part

      Control Range

      Diagnostic Note

      Front Fog Light Relay

      Front fog light relay

      ON/OFF

      -

      OK

      Front fog light relay operates (front fog lights come on).

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

    (Click here)

  2. READ VALUE USING INTELLIGENT TESTER (FRONT FOG LIGHT SWITCH)

    1. Using the intelligent tester, read the Data List (Click here).

      Table 2. Main Body

      Tester Display

      Measurement Item/Range

      Normal Condition

      Diagnostic Note

      Front Fog Light SW

      Front fog light switch signal / ON or OFF

      ON: Front fog light switch on

      OFF: Front fog light switch off

      -

      OK

      The display is as specified in the normal condition column.

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

    (Click here)

  3. INSPECT FRONT FOG LIGHT RELAY (FR FOG)

    E183428E15

    1. Remove the front fog light relay from the No. 4 relay block.

    2. 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 FRONT FOG LIGHT RELAY

  4. CHECK HARNESS AND CONNECTOR (BATTERY - FRONT FOG LIGHT RELAY [FR FOG])

    E142602E03

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      Front fog light relay terminal 5 - Body ground

      Always

      11 to 14 V

      Front fog light relay terminal 2 - Body ground

      Light control switch off

      Below 1 V

      Light control switch tail

      11 to 14 V
      Table 3. Text in Illustration

      *1

      No. 4 Relay Block

      *2

      Front Fog Light Relay (FR FOG)

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  5. CHECK HARNESS AND CONNECTOR (FRONT FOG LIGHT RELAY [FR FOG] - MAIN BODY ECU)

    U123646E01

    1. Disconnect the H81 main body ECU connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      Front fog light relay terminal 1 - H81-17 (FFGO)

      Always

      Below 1 Ω

      H81-17 (FFGO) - Body ground

      Always

      10 kΩ or higher
      Table 4. Text in Illustration

      *1

      Front view of wire harness connector

      (to Main Body ECU)

      *2

      No. 4 Relay Block

      *3

      Front Fog Light Relay (FR FOG)

      -

      -

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    U123640E02

    1. Reconnect the H81 main body ECU connector.

    2. Install the front fog light relay to the No. 4 relay block.

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      H81-17 (FFGO) - Body ground

      Light control switch in tail, front fog light switch off

      11 to 14 V

      Light control switch in tail, front fog light switch on

      Below 1 V
      Table 5. Text in Illustration

      *1

      Component with harness connected

      (Main Body ECU)

    REPAIR OR REPLACE HARNESS OR CONNECTOR (FRONT FOG LIGHT RELAY [FR FOG] - FOG LIGHT ASSEMBLY)

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)