LIGHTING SYSTEM Headlight Relay Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives headlight dimmer switch information signals, and illuminates the low beam headlight or high beam headlight.

WIRING DIAGRAM

A005JQKE02

CAUTION / NOTICE / HINT

Tech Tips

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

Note

Initialization is necessary when the main body ECU (multiplex network body ECU) is replaced Click here.*


  • *: w/ Automatic Light Control System

PROCEDURE


  1. CHECK VEHICLE CONDITION


    1. Check the illuminating condition of the low beam and high beam headlights.

      Result
      Result Proceed to

      Low beam headlights do not illuminate.

      (High beam headlights are normal.)

      		 A

      High beam headlights do not illuminate.

      (Low beam headlights are normal.)

      		 B
      Low beam headlights and high beam headlights do not illuminate. C

    B

    INSPECT HEADLIGHT DIMMER RELAY (DIM) Click here

    C

    INSPECT HEADLIGHT RELAY (H-LP/US-DRL) Click here

    A

  2. INSPECT HEADLIGHT DIMMER RELAY (DIM)


    1. Remove the headlight dimmer relay from the No. 2 engine room relay block.

    2. Inspect the headlight dimmer relay Click here.


    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

    REPLACE HEADLIGHT DIMMER RELAY

  3. INSPECT HEADLIGHT DIMMER RELAY (DIM)


    1. Remove the headlight dimmer relay from the No. 2 engine room relay block.

    2. Inspect the headlight dimmer relay Click here.


    NG

    REPLACE HEADLIGHT DIMMER RELAY

    OK

  4. CHECK HARNESS AND CONNECTOR (BATTERY - DIMMER RELAY)

    A005IQXE02
    Text in Illustration
    *a

    No. 2 Engine Room Relay Block

    (DIM Relay Terminal)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      Relay terminal 2 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (DIMMER RELAY - INSTRUMENT PANEL JUNCTION BLOCK)


    1. Disconnect the 3C instrument panel junction block assembly connector.

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

      A005IBIE02
      Text in Illustration
      *a

      No. 2 Engine Room Relay Block

      (DIM Relay Terminal)

      		 *b

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)
      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      Relay terminal 1 - 3C-35 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      3C-35 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY


    1. Remove the instrument panel junction block assembly Click here.

    2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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

      A005HBTE02
      Text in Illustration
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      3C-35 - MB-22 (DIM) Always Below 1 Ω

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here

  7. INSPECT HEADLIGHT RELAY (H-LP/US-DRL)


    1. Remove the headlight relay from the No. 2 engine room relay block.

    2. Inspect the headlight relay Click here.


    NG

    REPLACE HEADLIGHT RELAY

    OK

  8. INSPECT HEADLIGHT DIMMER RELAY (DIM)


    1. Remove the headlight dimmer relay from the No. 2 engine room relay block.

    2. Inspect the headlight dimmer relay Click here.


    NG

    REPLACE HEADLIGHT DIMMER RELAY

    OK

  9. CHECK HARNESS AND CONNECTOR (BATTERY - HEADLIGHT RELAY, DIMMER RELAY)


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

      A005LVHE01
      Text in Illustration
      *a

      No. 2 Engine Room Relay Block

      (H-LP/US-DRL Relay Terminal)

      		 *b

      No. 2 Engine Room Relay Block

      (DIM Relay Terminal)
      Standard Voltage
      H-LP/US-DRL Relay Terminal
      Tester Connection Condition Specified Condition
      Relay Terminal 1 - Body Ground Always 11 to 14 V
      Relay Terminal 5 - Body Ground Always 11 to 14 V
      DIM Relay Terminal
      Tester Connection Condition Specified Condition
      Relay Terminal 2 - Body Ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - DIMMER RELAY)


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

      A005LVHE01
      Text in Illustration
      *a

      No. 2 Engine Room Relay Block

      (H-LP/US-DRL Relay Terminal)

      		 *b

      No. 2 Engine Room Relay Block

      (DIM Relay Terminal)
      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      H-LP/US-DRL Relay Terminal 3 - DIM Relay Terminal 3 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      H-LP/US-DRL Relay Terminal 3 - Body Ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK - HEADLIGHT RELAY, DIMMER RELAY)


    1. Disconnect the 3C instrument panel junction block assembly connector.

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

      A005IVSE02
      Text in Illustration
      *a

      No. 2 Engine Room Relay Block

      (H-LP/US-DRL Relay Terminal)

      		 *b

      No. 2 Engine Room Relay Block

      (DIM Relay Terminal)
      *c

      Front view of wire harness connector

      (to Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      H-LP/US-DRL Relay Terminal 2 - 3C-18 Always Below 1 Ω
      DIM Relay Terminal 1 - 3C-35 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      3C-18 - Body ground Always 10 kΩ or higher
      3C-35 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY


    1. Remove the instrument panel junction block assembly Click here.

    2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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

      A005JV5E02
      Text in Illustration
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      3C-18 - MB-15 (HRLY) Always Below 1 Ω
      3C-35 - MB-22 (DIM) Always Below 1 Ω

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here