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NAVIGATION SYSTEM Vehicle Speed Signal Circuit between Navigation ECU and Combination Meter

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DTC Code DTC Name
  Vehicle Speed Signal Circuit between Navigation ECU and Combination Meter
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DESCRIPTION

The navigation ECU receives a vehicle speed signal from the combination meter assembly.

Tip:

  • 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 systems 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.

Table 1. *1 to Other Systems *2 Combination Meter Assembly *3 Navigation ECU
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WIRING DIAGRAM

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PROCEDURE


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    CHECK COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)


    1. B006620C92
      *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 O3-19 (+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 O3-19 (+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.
        Tip:

        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

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    CHECK HARNESS AND CONNECTOR (NAVIGATION ECU - COMBINATION METER ASSEMBLY)


    1. Disconnect the O150 navigation ECU connector.

    2. Disconnect the O3 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      O150-9 (SPD) - O3-19 (+S) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    • OK

      PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLEClick here

    • NG

      REPAIR OR REPLACE HARNESS OR CONNECTOR