AUDIO AND VISUAL SYSTEM(for Radio and Display Type) Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION



Tech Tips


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

B001N6NE05

PROCEDURE


  1. CHECK VEHICLE SIGNAL (OPERATION CHECK)


    1. B001LJM

      Enter the "Vehicle Signal Check Mode" screen. Refer to Check Vehicle Signal in Operation Check Click here.

    2. While driving the vehicle, compare the value displayed for "SPEED" to the reading on the speedometer. Check if these readings are almost equal.

      Tech Tips

      The combination meter assembly receives the vehicle speed signal from the skid control ECU via CAN communication. Therefore, perform the following inspection referring to values on the Data List of the skid control ECU because it is the source of the vehicle speed signal.

      OK
      Vehicle speed displayed on the "Vehicle Signal Check Mode" screen is almost the same as the actual vehicle speed measured using the GTS (See page Click here).

    OK
    NG
  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. B001LIWE01
      Text in Illustration
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the output waveform.


      1. Remove the combination meter assembly with the connector still connected.

      2. Connect an oscilloscope to terminal H19-40 (+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 H19-40 (+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
    OK
  3. INSPECT RADIO RECEIVER ASSEMBLY (INPUT WAVEFORM)


    1. Check the input waveform.

      B001M53E01

      1. Remove the radio receiver assembly with the connector still connected.

      2. Connect an oscilloscope to terminal H164-17 (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 H164-17 (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.

        Text in Illustration
        *a

        Component with harness connected

        (Radio Receiver Assembly)


    OK
    NG
  4. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - JUNCTION CONNECTOR)


    1. Disconnect the H164 radio receiver assembly connector.

    2. Disconnect the H117 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H164-17 (SPD) - H117-99 Always Below 1 Ω

    NG
    OK
  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - JUNCTION CONNECTOR)


    1. Disconnect the H19 combination meter assembly connector.

    2. Disconnect the H117 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H19-40 (+S) - H117-59 Always Below 1 Ω

    OK
    NG