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Engine does not Start [10/2022 - ]: Procedure

WARNING: This page is about a different car, the 2025 Lexus RX 350, 2024 Lexus RX 350, and 2023 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK WHETHER ENGINE STARTS 
    1. Using an electrical key transmitter sub-assembly which is registered to the vehicle, turn the ignition switch to ON.
    2. Check that the engine can be started 5 seconds after the ignition switch turned to ON.

      OK

      Engine starts normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    CHECK VEHICLE CONTROL HISTORY (ROB). Refer to  CHECK FOR INTERMITTENT PROBLEMS [10/2022 - ] 

    Result: 

    NG 

    See step  2

  2. CHECK SECURITY INDICATOR LIGHT (IMMOBILIZER FUNCTION UNSET) 
    1. Get into the vehicle while carrying an electrical key transmitter sub-assembly.
    2. Move the shift position to P.
    3. Press the engine switch with the brake pedal released and check that the security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      OK

      The security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      HINT: 

      The immobilizer function can be determined to be operating correctly if the security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO OTHER PROBLEM (Immobilizer System does not Operate Properly). Refer to  Immobilizer System does not Operate Properly [10/2022 - ]  

    Result: 

    OK 

    See step  3

  3. CHECK FOR DTC 
    1. Using the GTS, check if LIN communication DTC B2785-88 and B2789-87 are output.

      Body Electrical > Smart Access > Trouble Codes 

      OK

      DTC B2785-88 and B2789-87 are not output.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO LIN COMMUNICATION SYSTEM (DTC B2785-88). Refer to  DTC B2785-88: Communication between ECUs connected by LIN Bus off [10/2022 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK ENGINE CRANKING OPERATION 
    1. Get into the vehicle while carrying an electrical key transmitter sub-assembly.
    2. Move the shift position to P.
    3. Check that the key indicator display is displayed on the multi-information display in the combination meter assembly, and then press the engine switch and check that the engine cranks.

      Result

      Result Proceed to
      Engine cranks and initial combustion occurs A
      Engine cranks but initial combustion does not occur B
      Engine does not crank C

    Result: 

    A 

    GO TO OTHER PROBLEM (Immobilizer System does not Operate Properly). Refer to  Immobilizer System does not Operate Properly [10/2022 - ]  

    Result: 

    B 

    GO TO SFI SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - ] 

    Result: 

    C 

    See step  5

  5. CHECK ENGINE SWITCH CONDITION 
    1. Get into the vehicle while carrying an electrical key transmitter sub-assembly.
    2. Move the shift position to P.
    3. With the brake pedal released, check that pressing the engine switch causes the power source mode to change.

      Result

      Result Proceed to
      Power source mode changes : Off → ACC → ON → off A
      Power source mode does not change to ACC or ON B
      Power source mode changes to ON but not to ACC C
      Power source mode changes to ACC but not to ON D

    Result: 

    B 

    GO TO OTHER PROBLEM (Power Source Mode does not Change to ON (IG and ACC)). Refer to  Power Source Mode does not Change to ON (IG and ACC) [10/2022 - ]  

    Result: 

    C 

    GO TO OTHER PROBLEM (Power Source Mode does not Change to ON (ACC)). Refer to  Power Source Mode does not Change to ON (ACC) [10/2022 - ]  

    Result: 

    D 

    GO TO OTHER PROBLEM (Power Source Mode does not Change to ON (IG)). Refer to  Power Source Mode does not Change to ON (IG) [10/2022 - ]  

    Result: 

    A 

    See step  6

  6. READ VALUE USING GTS (STOP LIGHT SWITCH1) 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light Switch State of brake pedal OFF or ON OFF: Brake pedal released
      ON: Brake pedal depressed
      • Use this item to determine if the stop light switch assembly is malfunctioning.
      • The engine cannot be started when this item is OFF.
      • If the stop light switch assembly is malfunctioning, the engine can be started by pressing and holding the engine switch for a certain period of time.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Stop Light Switch

      OK

      The GTS display changes correctly in response to the brake pedal operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  20

    Result: 

    OK 

    See step  7

  7. READ VALUE USING GTS (SHIFT P SIGNAL CONDITION (LINE)) 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Shift P Signal Condition (Line) Shift position P Shift P, Other than shift P, Shift N or Other than shift P/N Shift P: Shift position in P
      Shift N: Shift position in N
      Other than shift P/N: Other than shift position in P or N      		 Use this item to determine if the shift position switch is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Shift P Signal Condition (Line)

      OK

      The GTS display changes correctly in response to the shift position operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  18

    Result: 

    OK 

    See step  8

  8. READ VALUE USING GTS (POWER SUPPLY CONDITION) 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Power Supply Condition Power supply state OFF, ACC ON, IGR ON, IGP ON or Starter ON OFF: Ignition switch off
      ACC ON: Ignition switch ACC
      IGR ON: Ignition switch ON
      IGP ON: Ignition switch ON
      Starter ON: Sending engine start request signal      		 -

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Power Supply Condition
      NOTE:

      Check that the key indicator display is displayed on the multi-information display in the combination meter assembly, and then press the engine switch.

      OK

      The GTS display changes correctly in response to the engine switch operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  17

    Result: 

    OK 

    See step  9

  9. INSPECT ST NO. 1 RELAY 

    Refer to ON-VEHICLE INSPECTION [10/2022 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE ST NO. 1 RELAY 

    Result: 

    OK 

    See step  10

  10. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ST NO. 1 RELAY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      ST NO. 1 relay terminal 2 - Body ground Engine switch pressed and held with brake pedal depressed (starter on) → Approximately 1 second after engine switch released (starter off) 6 V or higher* → 1.0 V or less
      GTY761650Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      (ST NO. 1 Relay Holder)

      HINT: 

      *: While the engine is cranking, the auxiliary battery voltage may drop to approximately 6 V.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  14

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (ST NO. 1 RELAY - AUXILIARY BATTERY AND GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      ST NO. 1 relay terminal 1 - Body ground Always Below 1 Ω
      GTY761650Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      (ST NO. 1 Relay Holder)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      ST NO. 1 relay terminal 5 - Body ground Ignition switch off 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  12

  12. CHECK HARNESS AND CONNECTOR (STARTER ASSEMBLY - ST NO. 1 RELAY) 
    1. Disconnect the B31 starter assembly connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      ST NO. 1 relay terminal 3 - B31-2 (SL1) Always Below 1 Ω
      ST NO. 1 relay terminal 3 or B31-2 (SL1) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (STARTER ASSEMBLY - AUXILIARY BATTERY) 
    1. Disconnect the B59 starter assembly connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      B59-1 (B) - Body ground Ignition switch off 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STARTER ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  14. CHECK ENGINE STOP AND START ECU 
    1. Disconnect the A25 engine stop and start ECU connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      ST NO. 1 relay terminal 2 - Body ground Engine switch pressed and held with brake pedal depressed (starter on) → Approximately 1 second after engine switch released (starter off) 6 V or higher* → 1.0 V or less
      GTY761650Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
      (ST NO. 1 Relay Holder)

      HINT: 

      *: While the engine is cranking, the auxiliary battery voltage may drop to approximately 6 V.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ENGINE STOP AND START ECU. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    See step  15

  15. INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A7-10 (STAR) - Body ground Engine switch pressed and held with brake pedal depressed (starter on) → Approximately 1 second after engine switch released (starter off) 6 V or higher* → 1.0 V or less

      HINT: 

      *: While the engine is cranking, the auxiliary battery voltage may drop to approximately 6 V.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 

    Result: 

    OK 

    See step  16

  16. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ST NO. 1 RELAY) 
    1. Disconnect the A7 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the A16 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A7-10 (STAR) - ST NO. 1 relay terminal 2 Always Below 1 Ω
      A7-10 (STAR) or ST NO. 1 relay terminal 2 - Other terminals and body ground Always 10 kΩ or higher
      A7-10 (STAR) - A25-21 (STA) Always Below 1 Ω
      A7-10 (STAR) or A25-21 (STA) - Other terminals and body ground Always 10 kΩ or higher
      A7-10 (STAR) - A7-3 (STA) Always Below 1 Ω
      A7-10 (STAR) or A7-3 (STA) - Other terminals and body ground Always 10 kΩ or higher
      A7-10 (STAR) - A16-16 (STA) Always Below 1 Ω
      A7-10 (STAR) or A16-16 (STA) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  17. CHECK SECURITY INDICATOR LIGHT (IMMOBILIZER FUNCTION UNSET) 
    1. Get into the vehicle while carrying an electrical key transmitter sub-assembly.
    2. Move the shift position to P.
    3. Press the engine switch with the brake pedal released and check that the security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      OK

      The security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      HINT: 

      The immobilizer function can be determined to be operating correctly if the security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [10/2022 - 08/2023]  , or refer to  REMOVAL [08/2023 - ] 

    Result: 

    NG 

    GO TO OTHER PROBLEM (Immobilizer System does not Operate Properly). Refer to  Immobilizer System does not Operate Properly [10/2022 - ]  

  18. CHECK TRANSMISSION FLOOR SHIFT ASSEMBLY 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      C51-14 (P) - Body ground Ignition switch ACC → ignition switch ON and Shift position in P Pulse generation (24 to 25 Hz or 30 to 31 Hz, High voltage: 9 V or more, Low voltage: below 1 V, duty ratio: 25 %)
      Ignition switch ACC → ignition switch ON and Shift position in N Pulse generation (24 to 25 Hz or 30 to 31 Hz, High voltage: 9 V or more, Low voltage: below 1 V, duty ratio: 55 %)
      Ignition switch ACC → ignition switch ON and Shift position in other then P or N Pulse generation (24 to 25 Hz or 30 to 31 Hz, High voltage: 9 V or more, Low voltage: below 1 V, duty ratio: 40 %)

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [10/2022 - 08/2023]  , or refer to  REMOVAL [08/2023 - ] 

    Result: 

    NG 

    See step  19

  19. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - TRANSMISSION FLOOR SHIFT ASSEMBLY) 
    1. Disconnect the C51 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the C35 transmission floor shift assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C51-14 (P) - C35-7 (PPOS) Always Below 1 Ω
      C51-14 (P) or C35-7 (PPOS) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE TRANSMISSION FLOOR SHIFT ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  20. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - POWER SOURCE AND BODY GROUND) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A32-1 (B) - Body ground Ignition switch off 11 to 14 V
      GTY1127521Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A32-3 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  21

  21. INSPECT STOP LIGHT SWITCH ASSEMBLY 

    Refer to ON-VEHICLE INSPECTION [10/2022 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    OK 

    See step  22

  22. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - STOP LIGHT SWITCH ASSEMBLY) 
    1. Disconnect the A7 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the A32 stop light switch assembly connector.
    3. Disconnect the A16 ECM connector.
    4. Disconnect the A31 skid control ECU (brake actuator assembly) connector.
    5. Disconnect the C35 transmission floor shift assembly connector.
    6. Disconnect the A74 semiconductor power integration ECU connector.
    7. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A7-21 (STP1) - A32-2 (L) Always Below 1 Ω
      A7-21 (STP1) or A32-2 (L) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [10/2022 - 08/2023]  , or refer to  REMOVAL [08/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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