2008 Lexus RX 400h FWDFACTORY OEM SERVICE PROCEDURE

Inspection Procedure

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

      OK: MIL lights up. 

    OK: SYSTEM OK 

    NG: Go to next step 

  2. CHECK COMMUNICATION BETWEEN TECHSTREAM AND HV CONTROL ECU 
    1. Connect Techstream to the DLC3.
    2. Turn the ignition switch to the ON position and turn the tester on.
    3. Check for communication between the tester and HV control ECU.

      Result 

      RESULT CHART

      Result Proceed to
      Communication is possible A
      Communication is not possible B

    A: GO TO MIL CIRCUIT 

    B: Go to next step 

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

      Result 

      RESULT CHART

      Result Proceed to
      MIL illuminates A
      MIL does not illuminate B
    4. Reconnect the throttle body connector.

    A: REPLACE THROTTLE BODY ASSEMBLY 

    B: Go to next step 

  4. CHECK MIL (VAPOR PRESSURE SENSOR) 
    1. Disconnect the vapor pressure sensor connector.
    2. Turn the ignition switch to the ON position.
    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 

  5. CHECK MIL (CANISTER PUMP MODULE) 
    1. Disconnect the canister pump module connector.
    2. Turn the ignition switch to the ON position.
    3. Check the MIL

      Result 

      RESULT CHART

      Result Proceed to
      MIL illuminates A
      MIL does not illuminate B
    4. Reconnect the canister pump module connector.
      Fig 1: Locating Canister Pump Module Connector
      G05200208Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    A: REPLACE CHARCOAL CANISTER ASSEMBLY 

    B: Go to next step 

  6. CHECK HARNESS AND CONNECTOR 
    1. Disconnect the throttle body connector.
    2. Disconnect the fuel tank pressure sensor connector.
    3. Disconnect the canister pump module connector.
    4. Disconnect the HV control ECU connectors.
    5. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for short) 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Specified Condition
      H32-18 (VC) - Body ground 10 kΩ or higher
    6. Reconnect the throttle body connector.
    7. Reconnect the fuel tank pressure sensor connector.
    8. Reconnect the canister pump module connector.
    9. Reconnect the HV control ECU connectors.
      10. Fig 2: Identifying Terminals Of HV Control ECU Connectors
      G05275749Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: REPLACE HV CONTROL ECU 

Factory Service Tools

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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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