Vehicle Speed Signal Circuit Between Navigation Receiver Assembly and Combination Meter

NAVIGATION / MULTI INFO DISPLAY: NAVIGATION SYSTEM: Vehicle Speed Signal Circuit between Navigation Receiver Assembly and Combination Meter

Vehicle Speed Signal Circuit between Navigation Receiver Assembly and Combination Meter

DESCRIPTION

This circuit sends a speed signal from the combination meter to the navigation receiver 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 its 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, both systems in the diagram below will not operate normally.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK OPERATION OF SPEEDOMETER
(a) Drive the vehicle and check if the function of the speedometer in the combination meter is normal.
OK:
Actual vehicle speed and the speed indicated on the speedometer are the same.

HINT:
- The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, refer to "Operation Check" in the meter/gauge system Component Tests and General Diagnostics.
- The vehicle speed sensor is functioning normally when the indication on the speedometer is normal.

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

2. INSPECT COMBINATION METER ASSEMBLY (SPEED SIGNAL)





(a) Disconnect the I6 navigation receiver assembly connector.
(b) Jack up the drive wheels.
(c) Move the shift lever to the neutral position.
(d) Turn the ignition switch to ON.
(e) Using an oscilloscope, check the signal waveform of the meter.

Waveform





HINT: As the vehicle speed increases, the wavelength shortens.

OK:
Voltage pulses as shown in the illustration
(f) Reconnect the navigation receiver assembly connector.

NG -- CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER - COMBINATION METER)
OK -- REPLACE NAVIGATION RECEIVER ASSEMBLY
3. CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER - COMBINATION METER)





(a) Disconnect the I6 navigation receiver assembly connector.
(b) Disconnect the H37 combination meter assembly connector.
(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





(d) Reconnect the navigation receiver assembly connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE NAVIGATION RECEIVER ASSEMBLY