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Home >> Lexus >> 2020 >> LC 500 >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System - Diagnostic Codes (Coupe) (2 Of 4) >> Electronically Controlled Brake System >> DTC C1246/46: Master Cylinder Pressure Sensor Malfunction; DTC C1364/61: Wheel Cylinder Pressure Sensor Malfunction [03/2017 - 09/2018] >> Procedure

DTC C1246/46: Master Cylinder Pressure Sensor Malfunction; DTC C1364/61: Wheel Cylinder Pressure Sensor Malfunction [03/2017 - 09/2018]: Procedure

  1. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - BRAKE ACTUATOR ASSEMBLY) 
    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 A11 and A8 skid control ECU assembly connectors.
    4. Disconnect the A7 brake actuator assembly connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A8-9 (VCM) - A7-10 (VCM) Always Below 1 Ω
      A8-9 (VCM) or A7-10 (VCM) - Body ground Always 10 kΩ or higher
      A8-21 (PAC1) - A7-15 (PAC1) Always Below 1 Ω
      A8-21 (PAC1) or A7-15 (PAC1) - Body ground Always 10 kΩ or higher
      A8-30 (PMC1) - A7-13 (PMC1) Always Below 1 Ω
      A8-30 (PMC1) or A7-13 (PMC1) - Body ground Always 10 kΩ or higher
      A8-32 (PFR) - A7-9 (PFR) Always Below 1 Ω
      A8-32 (PFR) or A7-9 (PFR) - Body ground Always 10 kΩ or higher
      A8-18 (PRL) - A7-11 (PRL) Always Below 1 Ω
      A8-18 (PRL) or A7-11 (PRL) - Body ground Always 10 kΩ or higher
      A8-8 (E) - A7-14 (E) Always Below 1 Ω
      A8-8 (E) or A7-14 (E) - Body ground Always 10 kΩ or higher
      A8-31 (PCK1) - A7-12 (PCK1) Always Below 1 Ω
      A8-31 (PCK1) or A7-12 (PCK1) - Body ground Always 10 kΩ or higher
      A11-16 (VCM2) - A7-5 (VCM2) Always Below 1 Ω
      A11-16 (VCM2) or A7-5 (VCM2) - Body ground Always 10 kΩ or higher
      A11-28 (PMC2) - A7-8 (PMC2) Always Below 1 Ω
      A11-28 (PMC2) or A7-8 (PMC2) - Body ground Always 10 kΩ or higher
      A11-23 (PFL) - A7-4 (PFL) Always Below 1 Ω
      A11-23 (PFL) or A7-4 (PFL) - Body ground Always 10 kΩ or higher
      A11-24 (PRR) - A7-6 (PRR) Always Below 1 Ω
      A11-24 (PRR) or A7-6 (PRR) - Body ground Always 10 kΩ or higher
      A11-15 (E2) - A7-16 (E2) Always Below 1 Ω
      A11-15 (E2) or A7-16 (E2) - Body ground Always 10 kΩ or higher
      A11-29 (PCK2) - A7-7 (PCK2) Always Below 1 Ω
      A11-29 (PCK2) or A7-7 (PCK2) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. READ VALUE USING TECHSTREAM (MASTER CYLINDER PRESSURE SENSOR, WHEEL CYLINDER PRESSURE SENSOR) 
    1. Reconnect the A11 and A8 skid control ECU assembly connectors.
    2. Reconnect the A7 brake actuator assembly connector.
    3. Connect the Techstream to the DLC3.
    4. Turn the engine switch on (IG).
    5. Select the Data List on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor 1 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      Master Cylinder Sensor2 Master cylinder pressure sensor 2 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FR W/C Sensor Front wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FL W/C Sensor Front wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      RR W/C Sensor Rear wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      RL W/C Sensor Rear wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      Master Cylinder Sensor
      Master Cylinder Sensor2
      FR W/C Sensor
      FL W/C Sensor
      RR W/C Sensor
      RL W/C Sensor
    6. Without operating the brake pedal, check the master cylinder sensor (PMC1), master cylinder sensor2 (PMC2), FR W/C sensor (PFR), FL W/C sensor (PFL), FL W/C sensor (PFL), RR W/C sensor (PRR) and RL W/C sensor (PRL).

      Standard voltage

      0.33 to 0.85 V

      Result

      Result Proceed to
      OK A
      Any single sensor is NG B
      Either master cylinder pressure sensor 1 system (master cylinder sensor (PMC1), FR W/C sensor (PFR), RL W/C sensor (PRL)) or master cylinder pressure sensor 2 system (master cylinder sensor2 (PMC2), FL W/C sensor (PFL), RR W/C sensor (PRR), or all NG C

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    C 

    See step  9

    Result: 

    A 

    See step  3

  3. CLEAR DTC 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Clear DTCs 

    2. Turn the engine switch off.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  4

  4. READ VALUE USING TECHSTREAM (MASTER CYLINDER PRESSURE SENSOR) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Select the Data List on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor 1 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      Master Cylinder Sensor2 Master cylinder pressure sensor 2 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      ECB Solenoid (SMC1) Master cut solenoid (SMC1) ON or OFF ON: Solenoid on (valve closed)
      OFF: Solenoid off (valve open)      		 ECB: Electronically Controlled Brake System
      ECB Solenoid (SMC2) Master cut solenoid (SMC2) ON or OFF ON: Solenoid on (valve closed)
      OFF: Solenoid off (valve open)      		 ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      Master Cylinder Sensor
      Master Cylinder Sensor2
      ECB Solenoid (SMC1)
      ECB Solenoid (SMC2)
      1. ECB: Electronically Controlled Brake System
    4. Check the output value of the master cylinder pressure sensor as the brake pedal is depressed.

      OK

      Output voltage is proportional to pedal stroke, and there is not a large difference in output between sensor 1 and sensor 2.

      HINT: 

      • If DTCs are stored due to the brake pedal being depressed, and electronically controlled brake system control is prohibited, check the Freeze Frame Data recorded at the time the DTCs were stored.
      • If the Freeze Frame Data shows that there are no abnormalities in the output of the master cylinder pressure sensors and difference in the output between sensor 1 and sensor 2, proceed to the next step.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  5

  5. READ VALUE USING TECHSTREAM (WHEEL CYLINDER PRESSURE SENSOR) 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Clear DTCs 

    2. Turn the engine switch off.
    3. Connect an LSPV gauge set.
    4. Turn the engine switch on (IG).
    5. Select the Data List on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      FR W/C Sensor Front wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FL W/C Sensor Front wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      RR W/C Sensor Rear wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      RL W/C Sensor Rear wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      FR W/C Sensor
      FL W/C Sensor
      RR W/C Sensor
      RL W/C Sensor
    6. Check the output values of the wheel cylinder pressure sensor at each hydraulic pressure level during the electronically controlled brake system control.

      Standard Voltage

      FOR FRONT WHEEL CYLINDER

      Hydraulic Pressure
      MPa (kgf/cm2 , psi)      		 FR W/C Sensor
      (Tester Display)      		 FL W/C Sensor
      (Tester Display)
      1.76(17.9, 255) 0.66 to 1.06 V 0.66 to 1.06 V
      5.22(53.2, 757) 1.37 to 1.77 V 1.37 to 1.77 V
      FOR REAR WHEEL CYLINDER

      Hydraulic Pressure
      MPa (kgf/cm2 , psi)      		 RR W/C Sensor
      (Tester Display)      		 RL W/C Sensor
      (Tester Display)
      1.76(17.9, 255) 0.66 to 1.06 V 0.66 to 1.06 V
      5.22(53.2, 757) 1.37 to 1.77 V 1.37 to 1.77 V

      HINT: 

      • If DTCs are stored due to the brake pedal being depressed, and electronically controlled brake system control is prohibited, check the Freeze Frame Data recorded at the time the DTCs were stored.
      • If the Freeze Frame Data shows that there are no abnormalities in the output of the wheel cylinder pressure sensors, proceed to the next step.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    OK 

    See step  6

  6. CHECK BRAKE MASTER CYLINDER SUB-ASSEMBLY AND MASTER CYLINDER PRESSURE SENSOR 
    1. Perform the Active Test "ECB Control Invalid".
      1. ECB: Electronically Controlled Brake System

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Control Invalid Electronically controlled brake system control invalid Control invalid ON/OFF
      • Electronically controlled brake system control is disabled (braking with no accumulator assist)
      • ECB: Electronically Controlled Brake System
    2. Depress the brake pedal and check the output value for the master cylinder sensor and FR W/C sensor, and the master cylinder2 and FL W/C sensor.

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor 1 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      Master Cylinder Sensor2 Master cylinder pressure sensor 2 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FR W/C Sensor Front wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FL W/C Sensor Front wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      ECB Control Invalid
      Data List Display
      Master Cylinder Sensor
      Master Cylinder Sensor2
      FR W/C Sensor
      FL W/C Sensor

      ECB: Electronically Controlled Brake System

      OK

      When FR W/C sensor is 1.0 V, master cylinder sensor is 1.5 to 1.9 V

      When FL W/C sensor is 1.0 V, master cylinder sensor2 is 1.5 to 1.9 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    OK 

    See step  7

  7. CLEAR DTC 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Clear DTCs 

    2. Turn the engine switch off.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  8

  8. RECONFIRM DTC 
    1. Start the engine.
    2. Perform a drive test and braking test.
    3. Check if the same DTC is output.

      Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Trouble Codes 

      Result

      Result Proceed to
      DTCs C1246/46 or C1364/61 are output. A
      DTCs C1246/46 and C1364/61 are not output. B

    Result: 

    B 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020] 

    Result: 

    A 

    See step  9

  9. CHECK FREEZE FRAME DATA 
    1. Check the INF Code (Information Code) from the freeze frame data when a DTC is stored.

      Result

      Result Proceed to
      Sensor power supply malfunction INF Code (191, 194, 221, 227, 233, 239) output A
      Sensor output malfunction INF Code output B

    Result: 

    A 

    REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

  10. READ VALUE USING TECHSTREAM (WHEEL CYLINDER PRESSURE SENSOR) 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Clear DTCs 

    2. Turn the engine switch off.
    3. Connect an LSPV gauge set.
    4. Turn the engine switch on (IG).
    5. Select the Data List on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      FR W/C Sensor Front wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FL W/C Sensor Front wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      RR W/C Sensor Rear wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      RL W/C Sensor Rear wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      FR W/C Sensor
      FL W/C Sensor
      RR W/C Sensor
      RL W/C Sensor
    6. Check the output values of the wheel cylinder pressure sensor at each hydraulic pressure level during the electronically controlled brake system control.

      Standard Voltage

      FOR FRONT WHEEL CYLINDER

      Hydraulic Pressure
      MPa (kgf/cm2 , psi)      		 FR W/C Sensor
      (Tester Display)      		 FL W/C Sensor
      (Tester Display)
      1.76(17.9, 255) 0.66 to 1.06 V 0.66 to 1.06 V
      5.22(53.2, 757) 1.37 to 1.77 V 1.37 to 1.77 V
      FOR REAR WHEEL CYLINDER

      Hydraulic Pressure
      MPa (kgf/cm2 , psi)      		 RR W/C Sensor
      (Tester Display)      		 RL W/C Sensor
      (Tester Display)
      1.76(17.9, 255) 0.66 to 1.06 V 0.66 to 1.06 V
      5.22(53.2, 757) 1.37 to 1.77 V 1.37 to 1.77 V

      HINT: 

      • If DTCs are stored due to the brake pedal being depressed, and electronically controlled brake system control is prohibited, check the Freeze Frame Data recorded at the time the DTCs were stored.
      • If the Freeze Frame Data shows that there are no abnormalities in the output of the wheel cylinder pressure sensors, proceed to the next step.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    OK 

    See step  11

  11. CHECK BRAKE MASTER CYLINDER SUB-ASSEMBLY AND MASTER CYLINDER PRESSURE SENSOR 
    1. Perform the Active Test "ECB Control Invalid".
      1. ECB: Electronically Controlled Brake System

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023]

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Control Invalid Electronically controlled brake system control invalid Control invalid ON/OFF
      • Electronically controlled brake system control is disabled (braking with no accumulator assist)
      • ECB: Electronically Controlled Brake System
    2. Depress the brake pedal and check the output value for the master cylinder sensor and FR W/C sensor, and the master cylinder2 and FL W/C sensor.

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Master Cylinder Sensor Master cylinder pressure sensor 1 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      Master Cylinder Sensor2 Master cylinder pressure sensor 2 Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FR W/C Sensor Front wheel cylinder pressure sensor RH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed
      FL W/C Sensor Front wheel cylinder pressure sensor LH Min.: 0.00 V, Max.: 5.00 V Brake pedal released: 0.30 to 0.70 V Reading increases when brake pedal is depressed

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      ECB Control Invalid
      Data List Display
      Master Cylinder Sensor
      Master Cylinder Sensor2
      FR W/C Sensor
      FL W/C Sensor
      1. ECB: Electronically Controlled Brake System

      OK

      When FR W/C sensor is 1.0 V, master cylinder sensor is 1.5 to 1.9 V

      When FL W/C sensor is 1.0 V, master cylinder sensor2 is 1.5 to 1.9 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE MASTER CYLINDER SUB-ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    NG 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

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