Vehicle Speed Signal Circuit Between Stereo Component Amplifier and Combination Meter (to 12/2010)

NAVIGATION: NAVIGATION 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 stereo component amplifier assembly receives a vehicle speed signal from the combination meter assembly to control the ASL function.

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 systems 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. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

(a) Check the output waveform.





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

(2) Connect an oscilloscope to terminal E30-5 (+S) and body ground.

(3) Turn the ignition switch to ON.

(4) Turn a wheel slowly.

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





Text in Illustration





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.

NG -- GO TO METER / GAUGE SYSTEM Speedometer Malfunction
OK -- Continue to next step.

2. INSPECT DIODE

(a) Check that the malfunction disappears when another diode in good condition is installed.

OK:

Malfunction disappears.

NG -- CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - DIODE)

OK -- END (DIODE WAS DEFECTIVE)

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

(a) Disconnect the E20 stereo component amplifier assembly connector.

(b) Disconnect the E55 diode 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.

4. CHECK HARNESS AND CONNECTOR (DIODE - COMBINATION METER ASSEMBLY)

(a) Disconnect the E55 diode connector.

(b) Disconnect the E30 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 -- REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Removal (to 12/2010)