Vehicle Speed Signal Circuit Between Stereo Component Amplifier and Combination Meter

AUDIO / VISUAL: AUDIO AND VISUAL SYSTEM: Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter
- Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter

DESCRIPTION

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

Speed signals are received from the combination meter and used for the ASL.

The ASL function automatically adjusts the sound volume in order to clear audio quality even when vehicle noise increases (as vehicle noise increases, the volume is turned up etc.).

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, all systems in the diagram below will not operate normally.

WIRING DIAGRAM

1. for 2GR-FE





2. for 1AR-FE





INSPECTION PROCEDURE

PROCEDURE

1. 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 terminals E1-9 (+S) and body ground.

(3) Ignition switch on (IG).

(4) Turn the wheel slowly.

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





OK:

The waveform is displayed as 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.

NG -- GO TO METER / GAUGE SYSTEM Speed Signal Circuit
OK -- Continue to next step.

2. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER - COMBINATION METER ASSEMBLY)

(a) Disconnect the stereo component amplifier connector and combination meter assembly connector.





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

Standard resistance:





NG -- CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER - JUNCTION CONNECTOR)

OK -- REPLACE RADIO RECEIVER

3. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER - JUNCTION CONNECTOR)

(a) Disconnect the junction connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STEREO COMPONENT AMPLIFIER - JUNCTION CONNECTOR)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (JUNCTION CONNECTOR)