Vehicle Speed Signal Circuit Between Stereo Component Amplifier and Combination Meter

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Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter

DESCRIPTION

The stereo component amplifier receiver 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

1. for 1AR-FE





2. for 2GR-FE





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)




(a) Check the input waveform.
(1) Reconnect the E1 connector.
(2) Remove the combination meter assembly with the connector(s) still connected.
(3) Connect an oscilloscope to terminal E1-16 (+S) and body ground.
(4) Turn the ignition switch to ON.
(5) Turn the wheel slowly.
(6) Check the signal waveform according to the condition(s) in the table below.





Text in Illustration





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
OK -- Continue to next step.

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




(a) Disconnect the E14 stereo component amplifier connector.




(b) Disconnect the E1 combination meter assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





Text in Illustration





NG -- CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER - NO. 1 JUNCTION CONNECTOR)
OK -- REPLACE STEREO COMPONENT AMPLIFIER
3. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER - NO. 1 JUNCTION CONNECTOR)




(a) Disconnect the E14 stereo component amplifier connector.




(b) Disconnect the E31 No. 1 junction block connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STEREO COMPONENT AMPLIFIER - NO. 1 JUNCTION CONNECTOR)
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 JUNCTION CONNECTOR)