Speed Signal Circuit

VEHICLE PROXIMITY NOTIFICATION SYSTEM: VEHICLE PROXIMITY NOTIFICATION SYSTEM: Speed Signal Circuit
- Speed Signal Circuit

DESCRIPTION

The vehicle approaching speaker controller receives the vehicle speed signal from the combination meter assembly.

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





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM)

(a) Check the input waveform.





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

(2) Connect an oscilloscope to terminal H19-39 (SI) and body ground.

(3) Turn the power switch on (IG).

(4) Turn the wheel slowly.

(5) 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 How To Proceed With Troubleshooting
OK -- Continue to next step.

2. CHECK HARNESS AND CONNECTOR (VEHICLE APPROACHING SPEAKER CONTROLLER - COMBINATION METER ASSEMBLY)

(a) Disconnect the H138 vehicle approaching speaker controller connector.

(b) Disconnect the H19 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 -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures