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Home >> Lexus >> 2008 >> IS F >> Repair and Diagnosis >> Brakes >> Brakes Control Systems >> Brake Control / Dynamic Control Systems >> Vehicle Stability Control System >> DTC C1246/46 Master Cylinder Pressure Sensor Malfunction; DTC C1281/81 Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC) >> Inspection Procedure

Inspection Procedure

NOTE: When replacing the skid control ECU, perform zero point calibration and store system information (See CALIBRATION  ).
  1. CHECK STOP LIGHT OPERATION 
    1. Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.

      OK 

      BRAKE PEDAL REFERENCE

      Condition Illumination Condition
      Brake pedal depressed ON
      Brake pedal released OFF

    NG: INSPECT STOP LIGHT CIRCUIT  (See PROBLEM SYMPTOMS TABLE )

    OK: Go to next step 

  2. READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH AND BRAKE PEDAL LOAD SENSING SWITCH) 
    1. Connect the Techstream to the DLC3
    2. Turn the engine switch on (IG)
    3. Select the Data List mode on the Techstream (See DATA LIST / ACTIVE TEST  ).

      ABS/VSC/TRAC 

      NORMAL CONDITION

      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch / ON or OFF ON Brake pedal depressed
      OFF Brake pedal released      		 -
      Brake Pedal Load Sensing SW Brake pedal load sensing switch / ON or OFF ON Brake pedal depressed beyond the specified point
      OFF Brake pedal not depressed beyond the specified point      		 -
    4. Check that the stop light switch display and brake pedal load sensing switch display observed on the Techstream change according to brake pedal operation

      OK: The Techstream displays ON or OFF according to brake pedal operation. 

    5. Slowly depress the brake pedal, and check when the stop light switch and brake pedal load sensing switch turn ON

      OK: The stop light switch should turn ON first, and then the brake pedal load sensing switch should turn ON. 

      Result 

      RESULT REFERENCE

      Result Proceed to
      OK A
      NG (The stop light switch does not turn on) B
      NG (The brake pedal load sensing switch turns on first) C

    B: Go to step  5

    C: Go to step  6

    A: Go to next step 

  3. READ VALUE USING TECHSTREAM (MASTER CYLINDER PRESSURE SENSOR) 
    1. Select the Data List mode on the Techstream (See DATA LIST / ACTIVE TEST  )

      ABS/VSC/TRAC 

      NORMAL CONDITION

      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor / Min 0 V, max 5 V When brake pedal is released 0 3 to 09V Reading increases when brake pedal is depressed
    2. Check that the brake fluid pressure value of the master cylinder pressure sensor observed on the Techstream changes when the brake pedal is depressed

      OK: When the pedal is depressed, voltage displayed on the Techstream increases. 

    NG: Go to step  7

    OK: Go to next step 

  4. RECONFIRM DTC 
    1. Turn the engine switch off.
    2. Clear the DTCs (See DTC CHECK / CLEAR  )
    3. Start the engine.
    4. Drive the vehicle at a speed of 30 km/h (18 mph) or more and perform braking test (decelerate the vehicle by depressing the brake pedal).
    5. Check if the same DTC is recorded (See DTC CHECK / CLEAR  ).

      Result 

      RESULT REFERENCE

      Result Proceed to
      DTC (C1246/46) is not output A
      DTC (C1246/46) is output B

    B: REPLACE SKID CONTROL ECU  (See REMOVAL  )

    A: CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)  (See DIAGNOSIS SYSTEM  )

  5. INSPECT SKID CONTROL ECU (STP1 TERMINAL) 
    1. Turn the engine switch off
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.
    3. Disconnect the skid control ECU connector
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage 

      STANDARD VOLTAGE

      Tester Connection Switch Condition Specified Condition
      J77-10 (STP1) - Body ground Stop light switch ON (Brake pedal depressed) 8 to 14 V
      J77-10 (STP1) - Body ground Stop light switch OFF (Brake pedal released) Below 1.5 V
      5. Fig 1: Identifying Skid Control ECU (STP1 Terminal)
      G05752616Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (STP1 CIRCUIT) 

    OK: REPLACE SKID CONTROL ECU  (See REMOVAL  )

  6. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION 
    1. Turn the engine switch off.
    2. Check the brake pedal height and stop light switch installation (See ADJUSTMENTINSPECTION )

      OK: The brake pedal height and stop light switch installation are normal. 

    NG: ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH  (See ADJUSTMENT )

    OK: REPLACE BRAKE PEDAL SUPPORT ASSEMBLY (BRAKE PEDAL LOAD SENSING SWITCH)  (See BRAKE PEDAL )

  7. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACTUATOR) 
    1. Turn the engine switch off
    2. Make sure that there is no looseness at the locking part and the connecting part of the connectors
    3. Disconnect the skid control ECU connector and the brake actuator connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      J78-18 (VCM) - A13-20 (VCM) Always Below 1 Ω
      J78-18 (VCM) - Body ground Always 10 kΩ or higher
      J78-4 (PMC) - A13-17 (PMC) Always Below 1 Ω
      J78-4 (PMC) - Body ground Always 10 kΩ or higher
      J78-6 (E2) - A13-19 (E2) Always Below 1 Ω
      J78-6 (E2) - Body ground Always 10 kΩ or higher
      5. Fig 2: Identifying Harness And Connector (Skid Control ECU - Brake Actuator)
      G05752617Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  8. INSPECT SKID CONTROL ECU (SENSOR INPUT) 
    1. Reconnect the skid control ECU connector and the brake actuator connector
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage 

      STANDARD VOLTAGE

      Tester Connection Switch Condition Specified Condition
      J78-18 (VCM) - Body ground Engine switch on (IG) 4.5 to 5 5 V
      4. Fig 3: Identifying Skid Control ECU (Sensor Input)
      G05752618Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE SKID CONTROL ECU  (See REMOVAL  )

    OK: Go to next step 

  9. INSPECT SKID CONTROL ECU (SENSOR OUTPUT) 
    1. Remove either the right or left front brake cylinder bleeder plug.
    2. Install the pressure gauge via the attachment, and bleed the gauge of air (See BLEEDING ).
    3. Measure the voltage according to the value(s) in the table below

      Standard Voltage 

      STANDARD VOLTAGE

      Tester Connection Fluid Pressure MPa (kgf/cm2 , psi) Specified Condition
      J78-4 (PMC) - Body ground 0 (0, 0) 0.37 to 0.63 V
      J78-4 (PMC) - Body ground 5.88 (60, 853) 1.57 to 1.83 V
      J78-4 (PMC) - Body ground 11.8(120,1707) 2.77 to 3.03 V
      4. Fig 4: Identifying Skid Control ECU (Sensor Output)
      G05752619Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE BRAKE ACTUATOR ASSEMBLY  (See REMOVAL  )

    OK: REPLACE SKID CONTROL ECU  (See REMOVAL  )

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