Inspection Procedure

2009 Toyota Avalon LimitedSECTION Inspection Procedure
  1. CHECK DTC OUTPUT 
    1. Delete the DTC (See DTC CHECK / CLEAR  ).

      HINT:

      After all DTCs are cleared, turn the engine switch on (IG) and depress the brake pedal. After 15 seconds have elapsed, check if the trouble occurs again.

    2. Check for DTCs again.

      OK: No DTC is output. 

    NG: Go to step 2 

    OK : END 

  2. INSPECT POWER SOURCE CONTROL ECU 
    1. Measure the voltage according to the value(s) in the table below.

      Voltage 

      TERMINAL SPECIFIED CONDITION CHART

      Terminal No. (Symbol) Condition Specified condition
      D44-39 (STSW) - Body ground Brake pedal depressed, Engine switch START 10 to 14 V

      HINT:

      Voltage is output for 0.3 seconds after engine start.

      Fig 1: Inspecting Power Source Control ECU
      G05000348Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE POWER SOURCE CONTROL ECU 

    OK: Go to next step 

  3. CHECK WIRE HARNESS (POWER SOURCE CONTROL ECU - ECM) 
    1. Disconnect the D44 ECU connector.
      Fig 2: Disconnecting D44 ECU Connector
      G05000349Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the A55 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Resistance 

      TERMINAL SPECIFIED CONDITION CHART

      Terminal No. (Symbol) Specified Condition
      D44-39 (STSW) - A55-14 (STSW) Below 1 Ω
      D44-39 (STSW) - Body ground 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 3: Identifying A55 ECM Connector
    G05405589Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  4. CHECK POWER SOURCE CONTROL ECU OPERATION 
    1. After replacing the power source control ECU with a normally functioning ECU, check that the engine can start.

      OK: Engine can start normally. 

    NG:  GO TO SFI SYSTEM

    OK : END (POWER SOURCE CONTROL ECU DEFECTIVE) 

RENDER: 1.0x

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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.