Vehicle Speed Signal Circuit between Navigation ECU and Combination Meter

DESCRIPTION

The navigation ECU receives a vehicle speed signal from the combination meter and information about the GPS antenna, and then adjusts vehicle position.

HINT:

1. 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.
   
2. If a short occurs in an ECU, all systems in the diagram below will not operate normally.
   

WIRING DIAGRAM

INSPECTION PROCEDURE

1. CHECK OPERATION OF SPEEDOMETER

1. 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 vehicle speed sensor is functioning normally when the indication on the speedometer is normal.

NG	GO TO COMBINATION METER SYSTEM

OK

2. INSPECT NAVIGATION ECU

1. Disconnect the navigation ECU connector N4.

2. Measure voltage.

   1. Jack up either one of the drive wheels.

   2. Move the shift lever to the neutral position.

   3. Turn the ignition switch to the ON position.

   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.
      

OK	REPLACE NAVIGATION ECU

NG

3. CHECK HARNESS AND CONNECTOR (COMBINATION METER - NAVIGATION ECU)

1. Disconnect the navigation ECU connector N4 and combination meter connector C8.

2. Measure the resistance according to the value(s) in the table below.

   Resistance:

   Tester connection	Condition	Specified condition
   SPD - C8-6	Ignition switch OFF	Below 1 Ω

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4. CHECK HARNESS AND CONNECTOR (COMBINATION METER - NAVIGATION ECU)

1. Disconnect the navigation ECU connector N4 and combination meter connector C8.

2. Measure the resistance according to the value(s) in the table below.

   Resistance:

   Tester connection	Condition	Specified condition
   SPD - Body ground	Ignition switch OFF	10 kΩ or higher

   HINT:

   If the resistance between terminal SPD and body ground is less than 10 kΩ, there may be a short in a wire harness, connector, or ECU.

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR OR EACH ECU

OK
REPLACE COMBINATION METER