Vehicle Speed Signal Circuit between Navigation ECU and Multi-Display

NAVIGATION / MULTI INFO DISPLAY: NAVIGATION SYSTEM: Vehicle Speed Signal Circuit between Navigation ECU and Multi-Display

Vehicle Speed Signal Circuit between Navigation ECU and Multi-Display

DESCRIPTION

The navigation ECU receives a vehicle speed signal from the multi-display and information from the GPS antenna, and then adjusts vehicle position.
HINT:
- A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter. The signal is changed to a pulse signal at the transistor in the combination meter. Each ECU controls the respective system based on the pulse signal.
- If a short occurs in an ECU, all systems in the diagram below will not operate normally.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK VEHICLE SIGNAL (DISPLAY CHECK MODE)





(a) Enter the "Display Check Mode (Vehicle Signal Check Mode)" Operation Check.
(b) While driving, compare the "SPEED" indicator to the reading on the speedometer. Check if these readings are almost the same.
OK:
The readings are almost the same.
NG -- GO TO "VEHICLE SPEED SIGNAL CIRCUIT BETWEEN MULTI-DISPLAY AND COMBINATION METER"
OK -- Continue to next step.
2. INSPECT NAVIGATION ECU





(a) Disconnect the navigation ECU connector.
(b) Measure voltage.
(1) Jack up either one of the drive wheels.
(2) Move the shift lever to N.
(3) Turn the engine switch on (IG).





(4) Measure the voltage between terminal SPD of the navigation ECU and body ground when the drive wheels are turned slowly.
OK:
Voltage pulses as shown in the illustration.
NG -- CHECK HARNESS AND CONNECTOR (NAVIGATION ECU - MULTI-DISPLAY)
OK -- REPLACE NAVIGATION ECU
3. CHECK HARNESS AND CONNECTOR (NAVIGATION ECU - MULTI-DISPLAY)





(a) Disconnect the multi-display connector and navigation ECU connector.





(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE MULTI-DISPLAY