LIGHTING SYSTEM Light Control Switch Circuit

DTC Code DTC Name
Light Control Switch Circuit

DESCRIPTION

The main body ECU receives the following signals:

  • Light control switch tail, head, or AUTO signal

  • Dimmer switch high or high flash signal

  • Front fog light switch signal*

  • Rear fog light switch signal

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).

  • When performing troubleshooting, inspect the switch that is related to the malfunction. For example, if both the right and left low beam headlights do not illuminate, read the light control switch head signal value in the Data List. If the value is normal, perform the headlight relay Active Test.

  • *: w/ Front Fog Light

WIRING DIAGRAM

E186279E07

PROCEDURE

  1. READ VALUE USING INTELLIGENT TESTER (HEADLIGHT DIMMER SWITCH ASSEMBLY)

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

      Table 1. Main Body

      Tester Display

      Measurement Item/Range

      Normal Condition

      Diagnostic Note

      Dimmer SW

      Dimmer switch high signal / ON or OFF

      ON: Dimmer switch in high or high flash

      OFF: Dimmer switch in low

      -

      Passing Light SW

      Dimmer switch high flash signal / ON or OFF

      ON: Dimmer switch in high flash

      OFF: Dimmer switch not in high flash

      -

      Rear Fog Light SW

      Rear fog light switch signal / ON or OFF

      ON: Rear fog light switch on

      OFF: Rear fog light switch off

      -

      Front Fog Light SW*1

      Front fog light switch signal / ON or OFF

      ON: Front fog light switch on

      OFF: Front fog light switch off

      -

      Auto Light SW*2

      Light control switch AUTO signal / ON or OFF

      ON: Light control switch in AUTO

      OFF: Light control switch not in AUTO

      -

      Head Light SW (Head)

      Light control switch head signal / ON or OFF

      ON: Light control switch in head

      OFF: Light control switch not in head

      -

      Head Light SW (Tail)

      Light control switch tail signal / ON or OFF

      ON: Light control switch in tail or head

      OFF: Light control switch not in tail or head

      -

      • *1: w/ Front Fog Light

      • *2: w/ Automatic Light Control System

      OK

      The display is as specified in the normal condition column.

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

    (Click here)

  2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

    1. Inspect the headlight dimmer switch assembly (Click here).

      OK

      Headlight dimmer switch assembly is normal.

    REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY

    (Click here)

  3. CHECK HARNESS AND CONNECTOR (DIMMER SWITCH - MAIN BODY ECU AND BODY GROUND)

    U123661E02

    1. Disconnect the H13 headlight dimmer switch assembly connector.

    2. Disconnect the H79 and H81 main body ECU connectors.

    3. Disconnect the DJ instrument panel junction block assembly connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      H13-2 (B) - H81-9 (RFOG)

      Always

      Below 1 Ω

      H13-4 (BFG) - H81-13 (FFOG)*1

      Always

      Below 1 Ω

      H13-11 (HU) - DJ-4 (HU)

      Always

      Below 1 Ω

      H13-17 (HF) - H79-22 (HF)

      Always

      Below 1 Ω

      H13-18 (T) - H79-21 (TAIL)

      Always

      Below 1 Ω

      H13-19 (A) - H81-18 (A)*2

      Always

      Below 1 Ω

      H13-20 (H) - H81-12 (HEAD)

      Always

      Below 1 Ω

      H13-2 (B) - Body ground

      Always

      10 kΩ or higher

      H13-4 (BFG) - Body ground

      Always

      10 kΩ or higher

      H13-11 (HU) - Body ground

      Always

      10 kΩ or higher

      H13-17 (HF) - Body ground

      Always

      10 kΩ or higher

      H13-18 (T) - Body ground

      Always

      10 kΩ or higher

      H13-19 (A) - Body ground*2

      Always

      10 kΩ or higher

      H13-20 (H) - Body ground

      Always

      10 kΩ or higher

      H13-12 (E) - Body ground

      Always

      Below 1 Ω

      H13-3 (LFG) - Body ground

      Always

      Below 1 Ω

      • *1: w/ Front Fog Light

      • *2: w/ Automatic Light Control System

      Table 2. Text in Illustration

      *1

      Front view of wire harness connector

      (to Main Body ECU)

      *2

      w/ Front Fog Light

      *3

      w/ Automatic Light Control System

      *4

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

      *5

      Front view of wire harness connector

      (to Headlight Dimmer Switch Assembly)

      -

      -

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    REPAIR OR REPLACE HARNESS OR CONNECTOR