NAVIGATION 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 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 meter circuit plate. The signal is changed to a pulse signal at the transistor in the meter circuit plate. Each ECU controls its respective systems based on this pulse signal.

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

WIRING DIAGRAM

A001UZ1E19
*1 Other ECUs
*2 Stereo Component Amplifier Assembly
*3 Combination Meter Assembly

PROCEDURE


  1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. Check the output waveform.


      1. Remove the combination meter assembly with the connector(s) still connected.

      2. A001YCMC38
        *a

        Component with harness connected

        (Combination Meter Assembly)

        Connect an oscilloscope to terminal F4-6 (+S) and body ground.

      3. Turn the Ignition switch ON.

      4. Turn a wheel slowly.

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

        Item Condition
        Measurement terminal F4-6 (+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.

      Result
      Proceed to
      OK
      NG

    NG

    GO TO METER / GAUGE SYSTEM Click here

    OK

  2. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (INPUT WAVEFORM)


    1. Check the input waveform.


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

      2. A001YCMC41
        *a

        Component with harness connected

        (Stereo Component Amplifier Assembly)

        Connect an oscilloscope to terminal F76-11 (SPD) and body ground.

      3. Turn the Ignition switch ON.

      4. Turn a wheel slowly.

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

        Item Condition
        Measurement terminal F76-11 (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.

      Result
      Proceed to
      OK
      NG

    OK

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

    NG

  3. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - COMBINATION METER ASSEMBLY)


    1. Disconnect the F76 stereo component amplifier assembly connector.

    2. Disconnect the F4 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F76-11 (SPD) - F4-6 (+S) Always Below 1 Ω
      F76-11 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR