AUDIO AND VISUAL SYSTEM Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter

DESCRIPTION

The stereo component amplifier assembly receives a vehicle speed signal from the No. 3 meter circuit plate to control the ASL function.

Tech Tips


  • A voltage of 12 V or 5 V is output from each ECU and then input to the No. 3 meter circuit plate. The signal is changed to a pulse signal at the transistor in the No. 3 meter circuit plate. Each ECU controls the respective systems 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

A01JCZ1E01

INSPECTION PROCEDURE

PROCEDURE


  1. INSPECT NO. 3 METER CIRCUIT PLATE (OUTPUT WAVEFORM)


    1. A01J8H5E12
      Text in Illustration
      *a

      Component with harness connected

      (No. 3 Meter Circuit Plate)

      Check the output waveform.


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

      2. Connect an oscilloscope to terminal L27-7 (+S) and body ground.

      3. Turn the power switch on (IG).

      4. Turn a wheel slowly.

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

        Item Condition
        Measurement terminal L27-7 (+S) - Body ground
        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

  2. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (INPUT WAVEFORM)


    1. A01J9ONE22
      Text in Illustration
      *a

      Component with harness connected

      (Stereo Component Amplifier Assembly)

      Check the input waveform.


      1. Remove the stereo component amplifier assembly with the connector(s) still connected.

      2. Connect an oscilloscope to terminal L143-11 (SPD) and body ground.

      3. Turn the power switch on (IG).

      4. Turn a wheel slowly.

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

        Item Condition
        Measurement terminal L143-11 (SPD) - Body ground
        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

    CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - NO. 3 METER CIRCUIT PLATE) Click here

    OK

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

  3. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - NO. 3 METER CIRCUIT PLATE)


    1. Disconnect the stereo component amplifier assembly connector.

    2. Disconnect the No. 3 meter circuit plate connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L143-11 (SPD) - L27-7 (+S) Always Below 1 Ω

    NG

    CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - NO. 4 JUNCTION BLOCK) Click here

    OK

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

  4. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - NO. 4 JUNCTION BLOCK)


    1. Disconnect the stereo component amplifier assembly connector.

    2. Disconnect the No. 4 junction block connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L143-11 (SPD) - 4A-69 Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK - NO. 4 JUNCTION BLOCK)


    1. Disconnect the No. 3 junction block connector.

    2. Disconnect the No. 4 junction block connector.

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

      Standard Resistance
      for LHD
      Tester Connection Condition Specified Condition
      3B-85 - 4A-21 Always Below 1 Ω
      for RHD
      Tester Connection Condition Specified Condition
      3B-82 - 4A-21 Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK NO. 4 JUNCTION BLOCK


    1. Disconnect the No. 4 junction block connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      4A-69 - 4A-21 Always Below 1 Ω

    NG

    REPLACE NO. 4 JUNCTION BLOCK

    OK

  7. CHECK NO. 3 JUNCTION BLOCK


    1. Disconnect the No. 3 junction block connector.

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

      Standard Resistance
      for LHD
      Tester Connection Condition Specified Condition
      3B-85 - 3A-26 Always Below 1 Ω
      for RHD
      Tester Connection Condition Specified Condition
      3B-82 - 3A-47 Always Below 1 Ω

    NG

    REPLACE NO. 3 JUNCTION BLOCK

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 3 METER CIRCUIT PLATE - NO. 3 JUNCTION BLOCK)