Vehicle Speed Signal Circuit Between Radio Receiver and Combination Meter

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 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.

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. 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.
* If a short occurs in any of the ECUs or in the wire harness connected to an ECU, related components will not operate normally.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
After replacing the radio receiver assembly of vehicles subscribed to pay-type satellite radio broadcasts, XM radio ID registration is necessary (w/ SDARS System).

PROCEDURE

1. CHECK OPERATION OF SPEEDOMETER

(a) Drive the vehicle and check if the function of the speedometer on the combination meter assembly 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.
* The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, refer to "On-Vehicle Inspection" in the meter/gauge system Meter / Gauge System.

NG -- GO TO METER / GAUGE SYSTEM How To Proceed With Troubleshooting
OK -- Continue to next step.

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

(a) Disconnect the R3 radio receiver assembly connector.

(b) Disconnect the C9 combination meter assembly connector.

(c) 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.

3. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

(a) Check the output waveform.





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

(2) Connect an oscilloscope to terminal C9-19 and body ground.

(3) Turn the ignition switch to ON.

(4) Turn the wheel slowly.

(5) 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

OK -- REPLACE RADIO RECEIVER ASSEMBLY Removal