NAVIGATION SYSTEM > 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 and information about the GPS antenna, and then adjusts vehicle position.

HINT:
  1. A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter. The signal is changed to a pulse signal at the transistor in the combination meter. Each ECU controls the respective system based on the pulse signal.
  2. If a short occurs in an ECU, all systems in the diagram below will not operate normally.


WIRING DIAGRAM


E110854E04


INSPECTION PROCEDURE

1.CHECK OPERATION OF SPEEDOMETER

  1. Drive the vehicle and check if the function of the speedometer in the combination meter is normal.

    OK:
    Actual vehicle speed and the speed indicated on the speedometer are the same.

    HINT:
    The vehicle speed sensor is functioning normally when the indication on the speedometer is normal.



NG
GO TO COMBINATION METER SYSTEM
OK


2.INSPECT NAVIGATION ECU


    E111733E05

  1. Disconnect the navigation ECU connector N4.



  1. Measure voltage.

    1. Jack up either one of the drive wheels.

    2. Move the shift lever to the neutral position.

    3. Turn the ignition switch to the ON position.



      4. E110855E01

    4. Measure the voltage between terminal SPD of the navigation ECU and body ground when the drive wheels are turned slowly.

      OK:
      Voltage pulses as shown in the illustration.



OK
REPLACE NAVIGATION ECU
NG


3.CHECK HARNESS AND CONNECTOR (COMBINATION METER - NAVIGATION ECU)


    E111763E02

  1. Disconnect the navigation ECU connector N4 and combination meter connector C8.

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

    Resistance:
    Tester connection
    		Condition
    		Specified condition
    SPD - C8-6
    		Ignition switch OFF
    		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4.CHECK HARNESS AND CONNECTOR (COMBINATION METER - NAVIGATION ECU)


    E111763E02

  1. Disconnect the navigation ECU connector N4 and combination meter connector C8.

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

    Resistance:
    Tester connection
    		Condition
    		Specified condition
    SPD - Body ground
    		Ignition switch OFF
    		10 kΩ or higher

    HINT:
    If the resistance between terminal SPD and body ground is less than 10 kΩ, there may be a short in a wire harness, connector, or ECU.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR OR EACH ECU
OK

REPLACE COMBINATION METER