Navigation System (For Radio And Display Type) Vehicle Speed Signal Circuit Between Radio Receiver And Combination Meter

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - COMBINATION METER ASSEMBLY)

DESCRIPTION

HINT:

1. 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 systems based on the pulse signal.
   
2. 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

INSPECTION PROCEDURE

1. Check the output waveform.
   

   1. Remove the combination meter assembly with the connector(s) still connected.
      

   2. Connect an oscilloscope to terminal G6-32 (+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	G6-32 (+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.
      

      HINT:

      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.

      Text in Illustration

      *a	Component with harness connected (Combination Meter Assembly)

1. Disconnect the H51 radio and display receiver assembly connector.
   

2. Disconnect the G6 combination meter assembly connector.
   

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

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   H51-17 (SPD) - G6-32 (+S)	Always	Below 1 Ω
   H51-17 (SPD) - Body ground	Always	10 kΩ or higher