2008 Toyota Prius BaseFACTORY OEM SERVICE PROCEDURE

Inspection Procedure

  1. CHECK MIL 
    1. Check that the MIL (Malfunction Indicator Lamp) lights up when turning the power switch ON (IG).

      OK: 

      MIL lights up. 

    OK: SYSTEM IS OK 

    NG: Go to next step. 

  2. CHECK CONNECTION BETWEEN TECHSTREAM AND ECM 
    1. Connect Techstream to the DLC3.
    2. Turn the power switch ON (IG) and turn Techstream ON.
    3. Check the connection between Techstream 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. CHECK ECM (VC VOLTAGE) 
    1. Turn the power switch ON (IG).
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      E4-18 (VC) - E5-28 (E1) Voltage is not 5 V
      Fig 1: Identifying E4 And E5 Connector Terminal
      G05188971Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. CHECK MIL (THROTTLE POSITION SENSOR) 
    1. Disconnect the T3 throttle body connector.
    2. Turn the power switch ON (IG).
    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 (WATER VALVE) 
    1. Disconnect the W5 water valve connector.
    2. Turn the power switch ON (IG).
    3. Check the MIL

      Result 

      RESULT CHART

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE WATER VALVE 

    B: Go to next step. 

  6. CHECK MIL (CANISTER PUMP MODULE) 
    1. Disconnect the V7 canister pump module connector.
    2. Turn the power switch ON (IG).
    3. Check the MIL

      Result 

      RESULT CHART

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE CHARCOAL CANISTER ASSEMBLY 

    B: Go to next step. 

  7. CHECK MIL (VAPOR PRESSURE SENSOR) 
    1. Disconnect the V6 vapor pressure sensor connector.
    2. Turn the power switch ON (IG).
    3. Check the MIL

      Result 

      RESULT CHART

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE VAPOR PRESSURE SENSOR 

    B: Go to next step. 

  8. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 
    1. Disconnect the T3 throttle body connector.
    2. Disconnect the W5 water valve connector.
    3. Disconnect the V7 canister pump module connector.
    4. Disconnect the V6 vapor pressure sensor connector.
    5. Disconnect the E4 ECM connector.
    6. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      E4-18 (VC) - Body ground 10 kΩ or higher
      Fig 2: Identifying E4 ECM Connector Terminal
      G05188972Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR 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.