AUDIO AND VISUAL SYSTEM (w/o 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 following diagram will not operate normally.

WIRING DIAGRAM

A015C7DE03

INSPECTION PROCEDURE

PROCEDURE


  1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. A015BLPE01
      Text in Illustration
      *1

      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 E7-4 (+S) and body ground.

      3. Turn the engine switch on (IG).

      4. Turn the wheel slowly.

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

        Item Condition
        Measurement terminal E7-4 (+S) - 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.


    NG

    GO TO METER / GAUGE SYSTEM Click here

    OK

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


    1. Disconnect the F18 stereo component amplifier assembly and E7 combination meter assembly connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F18-11 (SPD) - E7-4 (+S) Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here