2008 Lexus GX 470FACTORY OEM SERVICE PROCEDURE

Inspection Procedure

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

      OK: MIL lights up 

    OK: SYSTEM OK 

    NG: Go to Next Step 

  2. CHECK CONNECTION BETWEEN TECHSTREAM AND ECM 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch ON and tester ON.
    3. Check the communication between the Techstream and ECM.

      Result 

      RESULT REFERENCE

      Condition Proceed to
      Communication is possible A
      Communication is impossible B

    A: GO TO MIL CIRCUIT 

    B: Go to Next Step 

  3. INSPECT ECM 
    1. Turn the ignition switch ON.
    2. Measure the voltage between E5-23 (VC) and E7-1 (E1) of the ECM connectors.

      Standard voltage: 

      Voltage is not 5 V 

      Fig 1: Inspecting ECM
      G05264279Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. CHECK MIL (THROTTLE POSITION SENSOR) 
    1. Disconnect the T2 throttle body connector.
    2. Turn the ignition switch ON.
    3. Check the MIL.

      Result 

      RESULT REFERENCE

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE THROTTLE BODY 

    B: Go to Next Step 

  5. CHECK MIL (CAMSHAFT POSITION SENSOR) 
    1. Disconnect the C1 camshaft position sensor connector.
    2. Turn the ignition switch ON.
    3. Check the MIL

      Result 

      RESULT REFERENCE

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE CAMSHAFT POSITION SENSOR 

    B: Go to Next Step 

  6. CHECK MIL (CANISTER PUMP MODULE) 
    1. Remove the spare tire.
    2. Disconnect the L4 canister pump module connector.
    3. Turn the ignition switch ON
    4. Check the MIL.
      Fig 2: Checking MIL (Canister Pump Module)
      G05843753Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Result 

      RESULT REFERENCE

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE CANISTER 

    B: Go to Next Step 

  7. CHECK MIL (PRESSURE SENSOR) 
    1. Remove the intake manifold (see REMOVAL ).
    2. Disconnect the A45 pressure sensor connector.
    3. Turn the ignition switch ON.
    4. Check the MIL

      Result 

      RESULT REFERENCE

      Condition Proceed to
      MIL illuminates A
      MIL does not illuminate B

    A: REPLACE AIR PRESSURE SENSOR 

    B: Go to Next Step 

  8. CHECK HARNESS AND CONNECTOR 
    1. Disconnect the T2 throttle body connector.
    2. Disconnect the C1 camshaft position sensor connector
    3. Disconnect the L4 canister pump module connector.
    4. Disconnect the A45 pressure sensor.
    5. Disconnect the E5 ECM connector.
    6. Measure the resistance of the wire harness side connector.

      Standard resistance (check for short) 

      STANDARD VOLTAGE

      Tester Connection Specified Condition
      VC (E5-23) - Body ground 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 3: Checking Harness And Connector
    G05264281Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: REPLACE ECM 

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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