LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2012 >> IS 250C Automatic Trans >> Repair and Diagnosis >> Engine Mechanical >> Starter >> Smart Access System With Push-Button Start (For Start Function) (Diagnostic Codes & Symptom Tests) >> SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Start Function) >> Symptom Tests >> Power Source Mode does not Change >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Power Source Mode does not Change: Procedure

  1. CHECK FOR DTC 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Check for DTCs 5 seconds after the engine switch is turned on (IG).
      RESULT

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

    NG → See step   18 

    OK: Go to next step 

  2. CHECK SMART ACCESS SYSTEM WITH PUSH-BUTTON START (FOR START FUNCTION) 
    1. Remove the battery of the electrical key transmitter. Refer to REPLACEMENT .
      Fig 1: Operating Push Button Start Function When Key Battery Is Low
      GTY269473Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Touch the logo side mark of the key or card key to the engine switch.
    3. Check that the engine switch can be turned on (IG).
      RESULT

      Inspection Result Proceed to
      Power source mode does not change to on (ACC) A
      Power source mode does not change to on (IG) B
      Power source mode does not change to on (IG and ACC) C
      Power source mode is turned on D

    B → See step   7 

    C → See step   15 

    D → See step   19 

    A: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 
    1. Disconnect the J55 connector from the power source control ECU.
      Fig 2: J55 Connector Terminal Identification
      GTY272262Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage and resistance according to the value(s) in the table below.
      STANDARD VOLTAGE

      Tester Connection Condition Specified Condition
      J55-33 (AM1) - Body ground Always 11 to 14 V
      J55-12 (AM2) - Body ground Always 11 to 14 V
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-6 (GND2) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 

    OK: Go to next step 

  4. CHECK MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) 
    1. Disconnect the RD and RA connectors.
      Fig 3: RD And RA Connector Terminal Identification
      GTY281191Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      RD-2 - RA-5 or RD-7 Always 68 to 175 Ω
      RD-2, RA-5 or RD7 - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Main Body ECU RH (Cowl Side Junction Block RH))

    NG → REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - MAIN BODY ECU RH AND BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 4: J55, RD And RA Connector Terminal Identification
      GTY254910Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-11 (ACCD) - RD-2 Always Below 1 Ω
      J55-11 (ACCD) or RD-2 - Body ground Always 10 kΩ or higher
      RA-5 or RD-7 - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Power Source Control ECU)      		 *2 Front view of wire harness connector
      (to Main Body ECU RH (Cowl Side Junction Block RH))

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - MAIN BODY ECU RH) 

    OK: Go to next step 

  6. CHECK POWER SOURCE CONTROL ECU 
    1. Reconnect the J55 connector to the power source control ECU.
      Fig 5: J55 Connector Terminal Identification
      GTY274674Courtesy 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
      J55-11 (ACCD) - J55-6 (GND2) Engine Switch on (ACC) 8 to 14 V
      TEXT IN ILLUSTRATION

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

    NG → See step   20 

    OK → REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) 

  7. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 
    1. Disconnect the J55 connector from the power source control ECU.
      Fig 6: J55 Connector Terminal Identification
      GTY272261Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage and resistance according to the value(s) in the table below.
      STANDARD VOLTAGE

      Tester Connection Condition Specified Condition
      J55-33 (AM1) - Body ground Always 11 to 14 V
      J55-12 (AM2) - Body ground Always 11 to 14 V
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-6 (GND2) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 

    OK: Go to next step 

  8. CHECK MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) 
    1. Disconnect the RD and RA connectors from the main body ECU RH (cowl side junction block RH).
      Fig 7: Main Body ECU RH (Cowl Side Junction Block RH) Connector Terminal Identification
      GTY287808Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      RD-6 - RA-5 Always 68 to 175 Ω
      RD-6 - RD-12 Always Below 1 Ω
      RD-6 or RD-12 - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Component without harness connected
      (Main Body ECU RH (Cowl Side Junction Block RH))

    NG → REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH) 

    OK: Go to next step 

  9. CHECK MAIN BODY ECU LH (COWL SIDE JUNCTION BLOCK LH) 
    1. Disconnect the LD connector.
      Fig 8: Main Body ECU LH (Cowl Side Junction Block LH) Connector Terminal Identification
      GTY273014Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      LD-13 - LD-8 Always 68 to 175 Ω
      LD-13 or LD-8 - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Component without harness connected
      (Main Body ECU LH (Cowl Side Junction Block LH))

    NG → REPLACE MAIN BODY ECU LH (COWL SIDE JUNCTION BLOCK LH) 

    OK: Go to next step 

  10. INSPECT IG2 RELAY 
    1. Remove the IG2 relay from the engine room relay block No. 2.
      Fig 9: Starter Relay Connector Terminal Identification
      GTY100961Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      3 - 5 Battery voltage is not applied between terminals 1 and 2 10 MΩ or higher
      3 - 5 Battery voltage is applied between terminals 1 and 2 Below 1 Ω

    NG → REPLACE IG2 RELAY 

    OK: Go to next step 

  11. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - MAIN BODY ECU RH AND BODY GROUND) 
    1. Disconnect the RA connector from the main body ECU RH (cowl side junction block RH).
      Fig 10: J55, RD And RA Connector Terminal Identification
      GTY285070Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-34 (IG1D) - RD-6 Always Below 1 Ω
      J55-34 (IG1D) or RD-2 - Body ground Always 10 kΩ or higher
      RA-5 or RD-7 - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Power Source Control ECU)
      *2 Front view of wire harness connector
      (to Cowl Side Junction Block RH)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - MAIN BODY ECU RH AND BODY GROUND) 

    OK: Go to next step 

  12. CHECK HARNESS AND CONNECTOR (COWL SIDE JUNCTION BLOCK RH - COWL SIDE JUNCTION BLOCK LH) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 11: RD And LD Connector Terminal Identification
      GTY279422Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      RD-12 - LD-13 Always Below 1 Ω
      RD-12 or LD-13 - Body ground Always 10 kΩ or higher
      LD-8 or LD-9 - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Cowl Side Junction Block RH)
      *2 Front view of wire harness connector
      (to Cowl Side Junction Block LH)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (COWL SIDE JUNCTION BLOCK RH - COWL SIDE JUNCTION BLOCK LH) 

    OK: Go to next step 

  13. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ENGINE ROOM RELAY BLOCK NO. 2) 
    1. Remove the IG2 relay from the engine room relay block No. 2.
      Fig 12: J55 Connector Terminal Identification And Engine Room Relay Block
      GTY284068Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-35 (IG2D) - Engine room relay block IG2 relay terminal 2 Always Below 1 Ω
      J55-35 (IG2D) or Engine room relay block IG2 relay terminal 2 - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Front view of wire harness connector
      (to Power Source Control ECU)      		 *2 Component without harness connected
      (Engine Room Relay Block)

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - ENGINE ROOM RELAY BLOCK NO. 2)) 

    OK: Go to next step 

  14. CHECK POWER SOURCE CONTROL ECU 
    1. Reconnect the J55 connector to the power source control ECU.
      Fig 13: J55 Connector Terminal Identification
      GTY274681Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.
      STANDARD VOLTAGE

      Tester Connection Switch Condition Specified Condition
      J55-34 (IG1D) - Body ground Engine switch on (IG) 8 to 14 V
      J55-35 (IG2D) - Body ground Engine switch on (IG) 8 to 14 V
      TEXT IN ILLUSTRATION

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

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 

    OK → See step   21 

  15. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 
    1. Disconnect the J55 connector from the power source control ECU.
      Fig 14: J55 Connector Terminal Identification
      GTY272262Courtesy 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
      J55-33 (AM1) - Body ground Always 11 to 14 V
      J55-12 (AM2) - Body ground Always 11 to 14 V
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J55-6 (GND2) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

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

      HINT: 

      *1: Voltage is output only when the engine is cranking.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND) 

    OK: Go to next step 

  16. INSPECT ENGINE SWITCH 
    1. Remove the engine switch (for 2GR-FSE: Refer to REMOVAL , for 4GR-FSE: Refer to REMOVAL ).
      Fig 15: Engine Switch Connector Terminal Identification
      GTY260377Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.
      STANDARD RESISTANCE

      Tester Connection Switch Condition Specified Condition
      7 (SS1) - 5 (GND) Pushed Below 1 Ω
      2 (SS2) - 5 (GND) Pushed Below 1 Ω
      7 (SS1) - 5 (GND) Not Pushed 10 kΩ or higher
      2 (SS2) - 5 (GND) Not Pushed 10 kΩ or higher
      TEXT IN ILLUSTRATION

      *1 Component without harness connected
      (Engine Switch)      		 - -
      RESULT

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

    B → See step   22 

    C → See step   24 

    A: Go to next step 

  17. CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ENGINE SWITCH) 
    1. Measure the resistance according to the value(s) in the table below.
      Fig 16: J55 And J31 Connector Terminal Identification
      GTY284811Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J31-7 (SS1) - J55-14 (SSW1) Always Below 1 Ω
      J31-2 (SS2) - J55-37 (SSW2) Always Below 1 Ω
      J31-5 (GND) - Body ground Always Below 1Ω
      J31-7 (SS1) or J55-14 (SSW1) - Body ground Always 10 kΩ or higher
      J31-2 (SS2) or J55-37 (SSW2) - Body ground Always 10 kΩ or higher
      TEXT IN ILLUSTRATION

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

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

    OK → See step   23 

  18. GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART 
  19. GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START (ROOM OSCILLATOR DOES NOT RECOGNIZE KEY). Refer to  Room Oscillator does not Recognize Key 
  20. REPLACE POWER SOURCE CONTROL ECU. Refer to  REMOVAL 
  21. REPLACE POWER SOURCE CONTROL ECU. Refer to  REMOVAL 
  22. REPLACE ENGINE SWITCH (for 2GR-FSE). Refer to  REMOVAL 
  23. REPLACE POWER SOURCE CONTROL ECU. Refer to  REMOVAL 
  24. REPLACE ENGINE SWITCH (for 4GR-FSE). Refer to  REMOVAL 
scientia non olet · About LEMON Manuals