AUDIO AND VISUAL SYSTEM (w/ Navigation System) - Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter

DESCRIPTION

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

Speed signals are received from the combination meter assembly 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 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 diagram below will not operate normally.

WIRING DIAGRAM

Audio And Visual System (W/ Navigation System) - Vehicle Speed Signal Circuit Between Stereo Component Amplifier And Combination Meter. AUDIO / VIDEO. Land Cruiser URJ200 URJ202 GRJ200 VDJ200

INSPECTION PROCEDURE

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

Disconnect the F74 stereo component amplifier assembly connector and E7 combination meter assembly connector.

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

Standard Resistance:
Tester Connection Condition Specified Condition
F74-17 (SPD) - F7-4 (+S) Always Below 1 Ω
F74-17 (SPD) - Body ground Always 10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

Reconnect the E7 combination meter assembly connector.

Audio And Visual System (W/ Navigation System) - Vehicle Speed Signal Circuit Between Stereo Component Amplifier And Combination Meter. AUDIO / VIDEO. Land Cruiser URJ200 URJ202 GRJ200 VDJ200

Check the input waveform.

Connect an oscilloscope to terminal F74-17 (SPD) and body ground.

Turn the engine switch on (IG).

Turn a wheel slowly.

Text in Illustration
*a	Front view of wire harness connector (to Stereo Component Amplifier Assembly)

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

Item	Condition
Measurement terminal	F74-17 (SPD) - Body ground
Tool setting	5 V/DIV., 20 ms./DIV.
Vehicle condition	Driving at approx. 20 km/h (12 mph)

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.

GO TO METER / GAUGE SYSTEM ()

REPLACE PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE ()

Tester Connection	Condition	Specified Condition
F74-17 (SPD) - F7-4 (+S)	Always	Below 1 Ω
F74-17 (SPD) - Body ground	Always	10 kΩ or higher