Brand:

Toyota

Model Name:

Yaris NCP90 91 92 93

Manual:

Repair Manual

Section:

1Nz-Fe Engine Control System

Title:

Sfi System

  1. Description

  2. Wiring diagram

  3. Inspection procedure

  4. Check mil

  5. Check communication between intelligent tester and ecm

  6. Check mil (throttle position sensor)

  7. Check mil (accelerator pedal position sensor)

  8. Check harness and connector (vc output circuit)

SFI SYSTEM > VC Output Circuit


​

DESCRIPTION

The ECM constantly generates 5 V power from the battery voltages supplied to the +B (BATT) terminal to operate the microprocessor. The ECM also provides this power to the sensors through the VC output circuit.

Check that Malfunction Indicator Lamp (MIL) lights up when turning the ignition switch to ON.OK:MIL lights up Yaris

When the VC circuit is short-circuited, the microprocessor in the ECM and sensors that are supplied with power through the VC circuit are inactivated because the power is not supplied from the VC circuit. Under this condition, the system does not start up and the MIL does not illuminate even if the system malfunctions.
HINT:
Under normal conditions, the MIL is illuminated for several seconds when the ignition switch is first turned to ON. The MIL goes off when the engine is started.

WIRING DIAGRAM


Check that Malfunction Indicator Lamp (MIL) lights up when turning the ignition switch to ON.OK:MIL lights up Yaris


INSPECTION PROCEDURE

1.CHECK MIL

  1. Check that Malfunction Indicator Lamp (MIL) lights up when turning the ignition switch to ON.

    OK:
    MIL lights up


OKnext
SYSTEM OK
NG
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2.CHECK COMMUNICATION BETWEEN INTELLIGENT TESTER AND ECM

  1. Connect an intelligent tester to the DLC3.

  1. Turn the ignition switch to ON and tester on.

  1. Check the communication between the tester and ECM.

    Result:
    Result
    		Proceed To
    Communication is possible
    		A
    Communication is not possible
    		B


Anext
GO TO MIL CIRCUIT (Click here)
B
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3.CHECK MIL (THROTTLE POSITION SENSOR)

  1. Disconnect the C17 throttle body connector.

  1. Turn the ignition switch to ON.

  1. Check the MIL.

    Result:
    Result
    		Proceed To
    MIL illuminates
    		A
    MIL does not illuminate
    		B

  1. Reconnect the throttle body connector.



Anext
REPLACE THROTTLE BODY ASSEMBLY (Click here)
B
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4.CHECK MIL (ACCELERATOR PEDAL POSITION SENSOR)

  1. Disconnect the A20 accelerator pedal position sensor connector.

  1. Turn the ignition switch to ON.

  1. Check the MIL.

    Result:
    Result
    		Proceed To
    MIL illuminates
    		A
    MIL does not illuminate
    		B

  1. Reconnect the accelerator pedal position sensor connector.



Anext
REPLACE ACCELERATOR PEDAL POSITION SENSOR (Click here)
B
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5.CHECK HARNESS AND CONNECTOR (VC OUTPUT CIRCUIT)

  1. Disconnect the C17 throttle body connector.

  1. Disconnect the A20 accelerator pedal position sensor connector.

  1. Disconnect the A21 and C20 ECM connectors. Yaris

  2. Disconnect the A21 and C20 ECM connectors.

  1. Check the resistance.

    Standard resistance (Check for short):
    Tester Connections
    		Specified Conditions
    VCTA (C20-67) - Body ground
    		10 kΩ or higher
    VCPA (A21-57) - Body ground
    VCP2 (A21-58) - Body ground

  1. Reconnect the throttle body connector.

  1. Reconnect the accelerator pedal position sensor connector.

  1. Reconnect the ECM connectors.



NGnext
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
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REPLACE ECM (Click here)