NAVIGATION SYSTEM Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

for Navigation Function:

• The radio and display receiver assembly receives a vehicle speed signal from the combination meter assembly and sends the signal to the navigation ECU.

for Automatic Sound Levelizer (ASL):

• This circuit is necessary for the Automatic Sound Levelizer (ASL) built into the radio and display receiver assembly.

  The Automatic Sound Levelizer (ASL) function automatically adjusts the audio system volume level in order to compensate for increased vehicle noise (vehicle noise tends to increase as vehicle speed increases). The ASL adjusts the volume level based upon vehicle speed signals sent from the combination meter assembly.

for "Bluetooth":

• Vehicle speed signals are received from the combination meter assembly and used to cancel "Bluetooth" function operation.

  The navigation ECU recognizes that the vehicle is being driven and makes it impossible to connect or register a "Bluetooth" device while driving.

WIRING DIAGRAM

PROCEDURE

1. CHECK VEHICLE SIGNAL (OPERATION CHECK)

   
   

   1. 

      Enter the "Vehicle Signal Check Mode" screen. Refer to Check Vehicle Signal in Operation Check.

      Click here

   2. While driving the vehicle, compare the value displayed for "SPEED" to the reading on the speedometer. Check if these readings are almost equal.

      Tech Tips

      The combination meter assembly receives the vehicle speed signal from the skid control ECU via CAN communication. Therefore, perform the following inspection referring to values on the Data List of the skid control ECU because it is the source of the vehicle speed signal.

      OK
      Vehicle speed displayed on the "Vehicle Signal Check Mode" screen is almost the same as the actual vehicle speed measured using the GTS.
      Click here Click here

      Result
      Proceed to OK NG

   
   

   OK

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

   NG

2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

   
   

   1. Check the output waveform.

      

      *a

      Component with harness connected (Combination Meter Assembly)

      -

      -

      
      

      1. Remove the combination meter assembly with the connector still connected.

      2. Connect an oscilloscope to terminal G13-19 (+S) and body ground.

      3. Turn the power 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	G13-19 (+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.

         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.

      Result
      Proceed to OK NG

   
   

   NG

   GO TO METER / GAUGE SYSTEM Click here

   OK

3. INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY (INPUT WAVEFORM)

   
   

   1. Check the input waveform.

      

      *a

      Component with harness connected (Radio and Display Receiver Assembly)

      -

      -

      
      

      1. Remove the radio and display receiver assembly with the connector still connected.

      2. Connect an oscilloscope to terminal G105-17 (SPD) and body ground.

      3. Turn the power 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	G105-17 (SPD) - 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.

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

   NG

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

   
   

   1. Disconnect the G105 radio and display receiver assembly connector.

   2. Disconnect the G13 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition G105-17 (SPD) - G13-19 (+S) Always Below 1 Ω

      Result
      Proceed to OK NG

   
   

   OK

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

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR