AUDIO AND VISUAL SYSTEM Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

The multi-media module receiver assembly receives a vehicle speed signal from the No. 1 meter ECU sub-assembly 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 No. 1 meter ECU sub-assembly. The signal is changed to a pulse signal at the transistor in the No. 1 meter ECU sub-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 diagram below will not operate normally.

WIRING DIAGRAM

A001BB5E85
*1 No. 1 Meter ECU Sub-assembly
*2 Multi-media Module Receiver Assembly

PROCEDURE


  1. CHECK NO. 1 METER ECU SUB-ASSEMBLY (OUTPUT WAVEFORM)


    1. A001B0CE05
      Text in Illustration
      *a

      Component with harness connected

      (No. 1 Meter ECU Sub-assembly)

      Check the output waveform.


      1. Remove the No. 1 meter ECU sub-assembly with the connector still connected.

      2. Connect an oscilloscope to terminal L10-10 (+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 L10-10 (+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.


    OK

    GO TO METER / GAUGE SYSTEM Click here

    NG

  2. CHECK HARNESS AND CONNECTOR (MULTI-MEDIA MODULE RECEIVER ASSEMBLY - NO. 1 METER ECU SUB-ASSEMBLY)


    1. Disconnect the L146 multi-media module receiver assembly connector.

    2. Disconnect the L10 No. 1 meter ECU sub-assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L146-56 (SPD) - L10-10 (+S) Always Below 1 Ω
      L146-56 (SPD) or L10-10 (+S) - Body ground Always 10 kΩ or higher

    OK

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR