AUDIO AND VISUAL SYSTEM(for 8 Inch Display) 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

B002ENOE38
*1 Combination Meter Assembly
*2 Radio Receiver Assembly

PROCEDURE


  1. CHECK VEHICLE SIGNAL (OPERATION CHECK)


    1. B002DG8

      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 in 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.
      Click here Click here
      Result
      Proceed to
      OK
      NG

    OK

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

    NG

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. B002E6UC52
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the output waveform.


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

        Click here

      2. Connect an oscilloscope to terminal K33-19 (+S) and body ground.

      3. Turn the engine 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 K33-19 (+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

  3. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)


    1. Disconnect the K57 radio receiver assembly connector.

    2. Disconnect the K33 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K57-56 (SPD) - K33-19 (+S) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO RECEIVER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (RADIO RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)