AUTOMATIC HEADLIGHT BEAM LEVEL CONTROL SYSTEM Speed Signal Circuit

DESCRIPTION

The headlight leveling ECU assembly receives the vehicle speed signal from the combination meter assembly.

Tech Tips


  • A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter. The signal is changed to a pulse signal at the transistor in the combination meter. Each ECU controls the respective system based on the pulse signal.

  • If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems in the diagram below will not operate normally.

WIRING DIAGRAM

A0042LRE01

INSPECTION PROCEDURE

PROCEDURE


  1. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / HL Auto Leveling / Data List.

    5. Read the display on the GTS.

      HL Auto Leveling
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Vehicle Speed Vehicle speed/0 to 327.67 km/h (203.61 mph) Condition can be displayed -
      OK
      Normal condition listed above is displayed.

    NG

    INSPECT COMBINATION METER ASSEMBLY (NO. 3 METER CIRCUIT PLATE) (OUTPUT WAVEFORM) Click here

    OK

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

  2. INSPECT COMBINATION METER ASSEMBLY (NO. 3 METER CIRCUIT PLATE) (OUTPUT WAVEFORM)


    1. A0041UWE83
      Text in Illustration
      *a

      Component with harness connected

      (Combination Meter Assembly (No. 3 Meter Circuit Plate))

      Check the output waveform.


      1. Remove the combination meter assembly (No. 3 meter circuit plate) with the connector still connected.

      2. Connect an oscilloscope to terminal L23-7 (+S) and body ground.

      3. Turn the power switch on (IG).

      4. Check the signal waveform according to the condition(s) in the table below.

        Item Condition
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition Wheel being rotated
        OK
        The waveform is similar to that shown in the illustration.

        Tech Tips

        When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.


    NG

    GO TO METER / GAUGE SYSTEM Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY - COMBINATION METER ASSEMBLY)


    1. Disconnect the L23 combination meter assembly connector.

    2. Disconnect the A63 headlight leveling ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A63-16 (SPDR) - L23-7 (+S) Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE HEADLIGHT LEVELING ECU ASSEMBLY Click here