Speed Signal Circuit

DESCRIPTION

The clearance warning ECU receives the vehicle speed signal from the combination meter.

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

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 signal is normal when the indication on the speedometer is normal.

2 INSPECT CLEARANCE WARNING ECU

1. 1
   Disconnect the clearance warning ECU connector C9.
2. 2
   Measure the voltage.
3. 3
   Jack up either one of the drive wheels.
4. 4
   Move the shift lever to the neutral position.
5. 5
   Turn the ignition switch to the ON position

   

6. 6
   Measure the voltage between terminal SPD of the clearance warning ECU and body ground when a drive wheel is turned slowly.

OK: Voltage pulses as shown.

3 CHECK HARNESS AND CONNECTOR (COMBINATION METER - CLEARANCE WARNING ECU)

1. 1
   Disconnect the combination meter C10 connector.
2. 2
   Measure the resistance according to the value(s) in the table below.

Standard resistance

4 CHECK HARNESS AND CONNECTOR (COMBINATION METER AND EACH ECU - BODY GROUND)

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

Standard resistance

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.

REPLACE COMBINATION METER