AUDIO AND VISUAL SYSTEM(w/ Navigation System) Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter

DESCRIPTION

The circuit is necessary for the Automatic Sound Levelizer (ASL) built into the stereo component amplifier assembly.

Speed signals are received from the combination meter assembly and used for the ASL.

The ASL function automatically adjusts the sound volume in order to clear audio quality even when vehicle noise increases (as vehicle noise increases, the volume is turned up etc.).

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 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

A01X1J2E08
*a to Multi-media Module Receiver Assembly
*b from Skid Control ECU
*c Combination Meter Assembly
*d Stereo Component Amplifier Assembly

PROCEDURE


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


    1. Disconnect the F74 stereo component amplifier assembly connector and E7 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F74-17 (SPD) - F7-4 (+S) Always Below 1 Ω
      F74-17 (SPD) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. Reconnect the E7 combination meter assembly connector.

    2. A01X4WCE01

      Check the input waveform.


      1. Connect an oscilloscope to terminal F74-17 (SPD) and body ground.

      2. Turn the engine switch on (IG).

      3. Turn a wheel slowly.

        Text in Illustration
        *a

        Front view of wire harness connector

        (to Stereo Component Amplifier Assembly)

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

        A01XA6PE03
        Item Condition
        Measurement terminal F74-17 (SPD) - Body ground
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition Driving at approx. 20 km/h (12 mph)
        OK
        The waveform is displayed as 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.


    OK

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

    NG

    GO TO METER / GAUGE SYSTEM Click here