2012 Lexus IS 250C Automatic TransFACTORY OEM SERVICE PROCEDURE

DTC B2275: STSW Monitor Malfunction: Procedure

  1. CHECK FOR DTC 
    1. Clear the DTC. Refer to DTC CHECK / CLEAR .
    2. Turn the engine switch on (IG).
    3. After 15 seconds have elapsed, check for DTCs.
      RESULT

      Result Proceed to
      DTC B2275 is not output. A
      DTC B2275 is output. B

    B → See step   2 

    A → See step   4 

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ECM) 
    1. Disconnect the J55 connector from the power source control ECU.
      Fig 1: J55 And A5 Connector Terminal Identification
      GTY259080Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the A5 connector from the ECM.
    3. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-39 (STSW) - A5-19 (STSW) Always Below 1 Ω
      J55-39 (STSW) or A5-19 (STSW) - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Power Source Control ECU)
      *2 Front view of wire harness connector
      (to ECM)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - ECM) 

    OK: Go to next step 

  3. CHECK POWER SOURCE CONTROL ECU 
    1. Reconnect the J55 connector to the power source control ECU.
      Fig 2: J55 Connector Terminal Identification
      GTY274680Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.
      STANDARD VOLTAGE

      Tester Connection Condition Specified Condition
      J55-39 (STSW) - Body ground for AT:
      Brake pedal depressed, engine switch hold on (ST)
      for MT:
      Clutch pedal depressed, engine switch hold on (ST)
      Output voltage at terminal AM1 or AM2 is -2 V or more.
      TEXT IN ILLUSTRATION

      *1 Component with harness connected
      (Power Source Control ECU)
      RESULT

      Result Proceed to
      OK (for 2GR-FSE) A
      OK (for 4GR-FSE) B
      NG C

    B → See step   7 

    C → See step   5 

    A → See step   6 

  4. USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING 
  5. REPLACE POWER SOURCE CONTROL ECU. Refer to  REMOVAL 
  6. REPLACE ECM (for 2GR-FSE). Refer to  REMOVAL 
  7. REPLACE ECM (for 4GR-FSE). Refer to  REMOVAL 
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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