Vehicle Speed Signal Circuit Between Radio Receiver and Combination Meter (to 12/2010)

AUDIO / VISUAL: AUDIO AND VISUAL SYSTEM: Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter
- Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter

DESCRIPTION

for Automatic Sound Levelizer (ASL):

* This circuit is necessary for the Automatic Sound Levelizer (ASL) built into the stereo component amplifier 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.

for "Bluetooth":

* 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
* 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.
* 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

PROCEDURE

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

(a) Disconnect the radio receiver assembly and combination meter assembly connectors.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

(a) Reconnect the combination meter assembly connector.

(b) Check the output waveform.





(1) Connect an oscilloscope to terminal E34-3 (SPD) and body ground.

(2) Turn the ignition switch to ON.

(3) Turn a wheel slowly.

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









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





NG -- REPLACE COMBINATION METER ASSEMBLY Removal (to 12/2010)

OK -- REPLACE RADIO RECEIVER ASSEMBLY Removal (to 12/2010)