Audio And Visual System (W/O Multi-Display) Vehicle Speed Signal Circuit Between Radio Receiver And Combination Meter

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

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

CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - NO. 4 JUNCTION BLOCK)

DESCRIPTION

1. This circuit is necessary for the Automatic Sound Levelizer (ASL) built into the radio 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 that it receives from the combination meter assembly.
   

1. Speed signals are received from the combination meter assembly and used to cancel "Bluetooth" function operation.
   The radio receiver assembly recognizes that the vehicle is being driven and makes it impossible to connect or register a "Bluetooth" device while driving.
   

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 system 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 following diagram will not operate normally.
   

WIRING DIAGRAM

INSPECTION PROCEDURE

1. Check the output waveform.
   

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

   2. Connect an oscilloscope to terminal E46-36 (+S) and body ground.
      

   3. Turn the ignition switch to ON.
      

   4. Turn a wheel slowly.
      

   5. Check the signal waveform according to the condition(s) in the table below.
      

      Item	Condition
      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 E114 radio receiver assembly connector (for 6 speakers (w/ USB audio system)).
   

2. Disconnect the E26 radio receiver assembly connector (for 6 speakers (w/o USB audio system) or 4 speakers).
   

3. Disconnect the E46 combination meter assembly connector.
   

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

   Standard Resistance:

   for 6 Speakers (w/ USB Audio System)

   Tester Connection	Condition	Specified Condition
   E114-17 (SPD) - E46-36 (+S)	Always	Below 1 Ω

   for 6 Speakers (w/o USB Audio System) or 4 Speakers

   Tester Connection	Condition	Specified Condition
   E26-3 (SPD) - E46-36 (+S)	Always	Below 1 Ω

5. Proceed to the next step based on the inspection result.
   

   Result:

   Condition	Proceed to
   OK	A
   NG (for TMC made)	B
   NG (except TMC made)	C

1. Disconnect the E114 radio receiver assembly connector (for 6 speakers (w/ USB audio system)).
   

2. Disconnect the E26 radio receiver assembly connector (for 6 speakers (w/o USB audio system) or 4 speakers).
   

3. Disconnect the 4A No. 4 junction block connector.
   

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

   Standard Resistance:

   for 6 Speakers (w/ USB Audio System)

   Tester Connection	Condition	Specified Condition
   E114-17 (SPD) - 4A-37	Always	Below 1 Ω

   for 6 Speakers (w/o USB Audio System) or 4 Speakers

   Tester Connection	Condition	Specified Condition
   E26-3 (SPD) - 4A-37	Always	Below 1 Ω