LIGHTING SYSTEM Headlight Relay Circuit

DESCRIPTION

The main body ECU receives the light control switch head signal to control the headlight relay. When the light control switch is in the AUTO position, the main body ECU receives the ambient light level signal from the automatic light control sensor to control the headlight relay.

Tech Tips


  • If a low beam headlight on only one side does not illuminate, inspect any bulb, fuse or wire harness that is related to the headlight.

  • If both the right and left low beam headlights do not illuminate when the light control switch is turned to the head position, perform the headlight relay Active Test and read the light control switch head signal value in the Data List to determine if the malfunction exists on either the switch side or the relay side.

WIRING DIAGRAM

A002NWEE01
A002NBAE02
for Halogen Headlight
*a from Battery
*b Headlight Assembly LH
*c Headlight Assembly RH
*d Main Body ECU (Instrument Panel Junction Block Assembly)

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 (HEADLIGHT RELAY)


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

      Main Body
      Tester Display Test Part Control Range Diagnostic Note
      Headlight Relay Headlight Relay ON / OFF -
      OK
      Headlight relay operates (low beam headlights illuminate).

    OK

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    NG

  2. INSPECT HEADLIGHT RELAY (H-LP)


    1. A002OPKE02

      Remove the headlight relay from the engine room No. 1 relay block, junction 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

    NG

    REPLACE HEADLIGHT RELAY

    OK

  3. CHECK HARNESS AND CONNECTOR (BATTERY - HEADLIGHT RELAY [H-LP])


    1. A002M52E02
      Text in Illustration
      *1 Engine Room No. 1 Relay Block, Junction Block
      *2 Headlight Relay (H-LP)

      Remove the headlight relay from the engine room No. 1 relay block, junction block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      Headlight relay terminal 1 - Body ground Always 11 to 14 V
      Headlight relay terminal 5 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY [H-LP] - MAIN BODY ECU)


    1. Remove the headlight relay from the engine room No. 1 relay block, junction block.

      A002QSOE02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Main Body ECU)

      		 *2 Engine Room No. 1 Relay Block, Junction Block
      *3 Headlight Relay (H-LP) - -

    2. Disconnect the H79 main body ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Headlight relay terminal 2 - H79-20 (HRLY) Always Below 1 Ω
      H79-20 (HRLY) - Body ground Always 10 kΩ or higher

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR