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 enable clear audio 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





INSPECTION PROCEDURE

PROCEDURE

1. CHECK SPEEDOMETER
(a) Drive the vehicle and check if the speedometer in the combination meter functions normally.
OK:
Actual vehicle speed and the speed indicated on the speedometer are the same.

HINT: The vehicle speed sensor is functioning normally when the indicated speed on the speedometer is accurate.

NG -- GO TO COMBINATION METER SYSTEM
OK -- Continue to next step.

2. INSPECT STEREO COMPONENT AMPLIFIER





(a) Disconnect the stereo component amplifier connector.
(b) Measure voltage.
(1) Jack up either one of the drive wheels.
(2) Move the shift lever to the neutral position.
(3) Turn the ignition switch on (IG).





(4) Measure the voltage between terminal SPD of the stereo component amplifier and body ground when the drive wheels are turned slowly.
OK:
Voltage pulses as shown in the illustration.
OK -- REPLACE STEREO COMPONENT AMPLIFIER

NG -- Continue to next step.

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





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

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





(a) Disconnect the stereo component amplifier connector and the combination meter connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





HINT: If the resistance between terminal SPD and the body ground is less than 10 kOhms, there may be a short in a wire harness, connector, or ECU.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR OR EACH ECU
OK -- REPLACE COMBINATION METER