LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2017 >> GS 350 Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Diagnostic Codes (7 Of 7) & Circuit Tests >> SFI System >> Circuit Tests >> Starter Signal Circuit [10/2015 - ] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Starter Signal Circuit [10/2015 - ]: Procedure

  1. CHECK WHETHER ENGINE CAN BE CRANKED 
    1. Check if the engine can be cranked.

      Result

      Result Proceed to
      Engine cannot be cranked A
      Engine can be cranked B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  2

  2. READ VALUE USING TECHSTREAM (STARTER SW) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / Starter SW.
    5. Check the value displayed on the Techstream when the engine switch is turned to the on (IG) and the engine is started.

      OK

      Condition Techstream Display (Starter SW)
      Engine switch on (IG) OFF
      Engine started ON

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  3

  3. INSPECT RELAY (ST RELAY) 
    1. Inspect the ST relay.

      Refer to ON-VEHICLE INSPECTION [10/2015 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE RELAY (ST RELAY) 

    Result: 

    OK 

    See step  4

  4. INSPECT STARTER ASSEMBLY 
    1. Inspect the starter assembly.

      Refer to INSPECTION [10/2015 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE STARTER ASSEMBLY. Refer to  REMOVAL [10/2015 - ] 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (ST RELAY - STARTER ASSEMBLY) 
    1. Remove the ST relay from the No. 1 engine room relay block and junction block assembly.
    2. Disconnect the starter assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 (ST relay) - F22-1 Always Below 1 Ω
      3 (ST relay) or F22-1 - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (BATTERY - STARTER ASSEMBLY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G3-1 - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (ST RELAY - BODY GROUND) 
    1. Remove the ST relay from the No. 1 engine room relay block and junction block assembly.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (ST relay) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH ASSEMBLY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ST RELAY) 
    1. Remove the ST relay from the No. 1 engine room relay block and junction block assembly.
    2. Disconnect the park/neutral position switch assembly connector.
    3. Disconnect the certification ECU (smart key ECU assembly) connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (for 2WD)

      Tester Connection Condition Specified Condition
      F48-5 (L) - 2 (ST relay) Always Below 1 Ω
      A34-7 (STA) - 2 (ST relay) Always Below 1 Ω
      F48-5 (L), A34-7 (STA) or 2 (ST relay) - Body ground and other terminals Always 10 kΩ or higher

      Standard Resistance (for AWD)

      Tester Connection Condition Specified Condition
      F115-5 (L) - 2 (ST relay) Always Below 1 Ω
      A34-7 (STA) - 2 (ST relay) Always Below 1 Ω
      F115-5 (L), A34-7 (STA) or 2 (ST relay) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (BATTERY - ST RELAY) 
    1. Remove the ST relay from the No. 1 engine room relay block and junction block assembly.
      GTY635527Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 No. 1 Engine Room Relay Block and Junction Block Assembly
      *2 ST Relay
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      5 (ST relay) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  10. INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY 
    1. Inspect the park/neutral position switch assembly.

      for 2WD: Refer to INSPECTION [09/2014 - ]

      for AWD: Refer to INSPECTION [09/2014 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY 

    for 2WD: Refer to REMOVAL [09/2014 - ]

    for AWD: Refer to REMOVAL [09/2014 - ]

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM - ST RELAY - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)) 
    1. Disconnect the park/neutral position switch assembly connector.
    2. Disconnect the ECM connector.
    3. Remove the ST relay from the No. 1 engine room relay block and junction block assembly.
    4. Disconnect the certification ECU (smart key ECU assembly) connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (for 2WD)

      Tester Connection Condition Specified Condition
      F48-5 (L) - A78-43 (STA) Always Below 1 Ω
      F48-5 (L), A78-43 (STA), 2 (ST relay) or A34-7 (STA) - Body ground and other terminals Always 10 kΩ or higher

      Standard Resistance (for AWD)

      Tester Connection Condition Specified Condition
      F115-5 (L) - A78-43 (STA) Always Below 1 Ω
      F115-5 (L), A78-43 (STA), 2 (ST relay) or A34-7 (STA) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  12

  12. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM) 
    1. Disconnect the park/neutral position switch assembly connector.
    2. Disconnect the certification ECU (smart key ECU assembly) connector.
    3. Disconnect the ECM connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (for 2WD)

      Tester Connection Condition Specified Condition
      A34-5 (STAR) - F48-4 (B) Always Below 1 Ω
      A34-5 (STAR) - F74-106 (NSW) Always Below 1 Ω
      A34-5 (STAR), F48-4 (B) or F74-106 (NSW) - Body ground and other terminals Always 10 kΩ or higher

      Standard Resistance (for AWD)

      Tester Connection Condition Specified Condition
      A34-5 (STAR) - F115-4 (B) Always Below 1 Ω
      A34-5 (STAR) - F74-106 (NSW) Always Below 1 Ω
      A34-5 (STAR), F115-4 (B) or F74-106 (NSW) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2014 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  13. READ VALUE USING TECHSTREAM (STARTER SW) 
    1. Connect the Techstream to DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / Starter SW.
    5. Check the value displayed on the Techstream when the engine switch is turned to the on (IG) and the engine is started.

      OK

      Condition Techstream Display (Starter SW)
      Engine switch on (IG) OFF
      Engine started ON

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2015 - 09/2018]  , or refer to  PROBLEM SYMPTOMS TABLE [09/2018 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ST RELAY - ECM) 

scientia non olet · About LEMON Manuals