2006 Scion tC AutomaticFACTORY OEM SERVICE PROCEDURE

VC Output Circuit: Wiring Diagram

Fig 1: VC Output Circuit - Wiring Diagram
G04221305Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  1. CHECK MIL 
    1. Check that MIL (Malfunction Indicator Lamp) lights up when turning the ignition switch ON.

    Standard: 

    MIL lights up 

    OK : SYSTEM OK 

    NG 

  2. CHECK CONNECTION BETWEEN INTELLIGENT TESTER AND ECM 
    1. Connect the intelligent tester to the DLC3.
    2. Turn the ignition switch ON and turn the intelligent tester ON.
    3. Check the communication between the intelligent tester and ECM.

      Result 

    RESULT CHART

    Condition Proceed To
    Communication is possible A
    Communication is not possible B

    A : GO TO MIL CIRCUIT 

    B : Go to next step 

  3. INSPECT ECM (VC VOLTAGE) 
    1. Turn the ignition switch ON.
    2. Measure the voltage of the ECM connector.

      Result 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Specified Condition
    E8-18 (VC) - E6-1(E1) Voltage is not 5 V
    Fig 2: Measuring Voltage Of ECM Connector
    G04221306Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NEXT 

  4. CHECK MIL (THROTTLE POSITION SENSOR) 
    1. Disconnect the T1 throttle body connector.
    2. Turn the ignition switch ON.
    3. Check the MIL.

      Result 

    RESULT CHART

    Condition Proceed To
    MIL illuminates A
    MIL does not illuminate B

    A : REPLACE THROTTLE BODY 

    B : Go to next step 

  5. CHECK MIL (CANISTER PUMP MODULE) 
    1. Disconnect the T1 throttle body connector.
    2. Turn the ignition switch ON.
    3. Check the MIL.

      Result 

    RESULT CHART

    Condition Proceed To
    MIL illuminates A
    MIL does not illuminate B

    A : REPLACE CANISTER 

    B : Go to next step 

  6. CHECK WIRE HARNESS (ECM - BODY GROUND) 
    1. Disconnect the T1 throttle body connector.
    2. Disconnect the L1 canister pump module connector.
    3. Disconnect the E8 ECM connector.
    4. Measure the resistance of the wire harness side connector.

    Standard resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Specified Condition
    E8-18 (VC) - Body ground 10 kΩ or higher

    NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK : REPLACE ECM 

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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