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Home › Lexus › 2008 › LS 600hL › Repair and Diagnosis › Accessories & Equipment › Cruise Control Systems › Cruise Control › Cruise Control System › DTC P0571 Stop Light Switch Circuit Malfunction › Inspection Procedure

Inspection Procedure

  1. READ VALUE USING Intelligent tester OR TECHSTREAM (STOP LIGHT SWITCH) 
    1. Check the DATA LIST for proper functioning of the stop light switch
      1. Intelligent tester

        CCS

        DIAGNOSTIC NOTE NORMAL CONDITION CHART

        Tester Display Measurement Item/Range Normal Condition
        STP LIGHT SW1 M Stop light switch signal (Main CPU)/ON or OFF ON Brake pedal is depressed
        OFF Brake pedal is released
      2. Techstream

      CCS

      DIAGNOSTIC NOTE NORMAL CONDITION CHART

      Tester Display Measurement Item/Range Normal Condition
      Stop Light SW M-CPU Stop light switch signal (Main CPU)/ON or OFF ON Brake pedal is depressed
      OFF Brake pedal is released

    OK: Display changes according to brake pedal operation described in the above table. 

    NG: Go to step 2 

    OK: REPLACE HYBRID VEHICLE CONTROL ECU  (See REMOVAL ).

  2. INSPECT FUSE (STOP, ECU-IG) 
    1. Remove the STOP fuse from the main body ECU.
    2. Remove the ECU-IG fuse from the engine room No. 2 junction block.
    3. Measure the resistance according to the value (s) in the table below

    Standard resistance

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    STOP fuse Always Below 1 Ω
    ECU-IG fuse Always Below 1 Ω

    NG: REPLACE FUSE 

    OK: Go to next step 

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY 
    1. Remove the stop light switch (see STOP LIGHT SWITCH ).
    2. Measure the resistance according to the value (s) in the table below.

    Standard resistance

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Switch Condition Specified Condition
    1 - 2 Pushed Below 1 Ω
    1 - 2 Not pushed 10 kΩ or higher
    3 - 4 Not pushed Below 1 Ω
    3 - 4 Pushed 10 kΩ or higher
    Fig 1: Identifying Stop Light Switch Pin
    G05776006Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE STOP LIGHT SWITCH ASSEMBLY  (See STOP LIGHT SWITCH ).

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BATTERY) 
    1. Disconnect the A75 and A76 ECU connectors.
    2. Measure the voltage according to the value (s) in the table below.

      Standard voltage

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      A75-1 (STP) - Body ground Brake pedal is depressed 11 to 14 V
      A75-1 (STP) - Body ground Brake pedal is released Below 1V
      A76-6 (ST1-) - Body ground Power switch is ON (IG), brake pedal is released 11 to 14 V
      A76-6 (ST1-) - Body ground Power switch is ON (IG), brake pedal is depressed Below 1 V
      Fig 2: Identifying A75 And A76 ECU Connectors
      G05776007Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: REPLACE HYBRID VEHICLE CONTROL ECU  (See REMOVAL ).

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