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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 C1252/52: Brake Booster Pump Motor on Time Abnormally Long; DTC C1253/53: Pump Motor Relay Malfunction [03/2017 - 09/2018] >> Procedure

DTC C1252/52: Brake Booster Pump Motor on Time Abnormally Long; DTC C1253/53: Pump Motor Relay Malfunction [03/2017 - 09/2018]: Procedure

  1. PERFORM ACTIVE TEST USING TECHSTREAM (ABS MOTOR RELAY) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Select the Active Test on the Techstream.

      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 Motor Relay ABS motor relay 1 Relay ON/OFF
      • Operation sound of relay (clicking sound) and pump motor can be heard
      • ECB: Electronically Controlled Brake System
      ECB Motor Relay2 ABS motor relay 2 Relay ON/OFF
      • Operation sound of relay (clicking sound) and pump motor can be heard
      • ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Motor Relay

      ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Motor Relay2

      ECB: Electronically Controlled Brake System

    4. Check the operation sound of the ABS motor relay and motor when operating it using the Techstream.

      OK

      The operation sound of the ABS motor relay and motor should be heard.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  2

  2. INSPECT BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connectors.
      GTY809473Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Brake Booster with Accumulator Pump Assembly)
    2. Disconnect the A48 and A49 brake booster with accumulator pump assembly connectors.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A48-2 (BM1) - A48-4 (GND1) Always Below 10 Ω
      A49-2 (BM2) - A49-1 (GND2) Always Below 10 Ω
      A48-2 (BM1) - A49-2 (BM2) Always Below 1 Ω
      A48-4 (GND1) - A49-1 (GND2) Always Below 1 Ω
      A48-2 (BM1) - A48-1 (MTT) Always 950 to 1050 Ω
      A49-2 (BM2) - A48-1 (MTT) Always 950 to 1050 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.
    2. Disconnect the A8 skid control ECU assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A8-29 (MTT) - A48-1 (MTT) Always Below 1 Ω
      A8-29 (MTT) or A48-1 (MTT) - Body ground Always 10 kΩ or higher
      A48-4 (GND1) - Body ground Always Below 1 Ω
      A49-1 (GND2) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR) 
    1. Reconnect the A8 skid control ECU assembly connector.
    2. Reconnect the A48 and A49 brake booster with accumulator pump assembly connectors.
    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
      Accumulator Sensor Accumulator pressure sensor Min.: 0.00 V, Max.: 5.00 V Specified value: 2.60 to 3.80 V When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      Accumulator Sensor
    6. Depress the brake pedal 4 or 5 times and operate the pump motor.
    7. Wait for 30 seconds without depressing the brake pedal.
    8. Check that the accumulator pressure sensor output value change is within the specified range.

      OK

      Accumulator pressure sensor output value change is less than 0.20 V.

      HINT: 

      • This inspection is performed to determine if a long-term power malfunction occurred when low pressure is detected due to a defective sensor, an internal leak in the brake actuator assembly, or deterioration of the accumulator.
      • External brake fluid leaks are suspected if the fluid level drops inside the brake master cylinder reservoir assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  6

    Result: 

    OK 

    See step  5

  5. RECONFIRM 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.
    3. Turn the engine switch on (IG).
    4. 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 C1252/52 and C1253/53 are not output. A
      DTCs C1252/52 and/or C1253/53 are output. B

    Result: 

    A 

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

    Result: 

    B 

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

  6. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Select the Active Test on the Techstream.

      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 Solenoid (SMC1) Master cut solenoid (SMC1) Solenoid ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Solenoid (SMC1)

      ECB: Electronically Controlled Brake System

      HINT: 

      The Active Test can be performed when the following conditions are met.

      • ABS main relay is on.
      • Shift position is in P.
      • Parking brake is applied.
      • Vehicle speed is 0 km/h (0 mph).
    2. Perform the Active Test of the solenoid using the Techstream.
    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
      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

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      FR W/C Sensor
    4. Check that the output value of the wheel cylinder pressure sensor does not increase.

      OK

      The output value of the wheel cylinder pressure sensor does not increase.

      HINT: 

      If output value increases, there may be brake fluid leaks in the brake actuator assembly.

      Result

      Result Proceed to
      The output values of the wheel cylinder pressure sensors do not increase. A
      The output value of the wheel cylinder pressure sensor increases. B

    Result: 

    B 

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

    Result: 

    A 

    See step  7

  7. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Select the Active Test on the Techstream.

      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 Solenoid (SMC2) Master cut solenoid (SMC2) Solenoid ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Solenoid (SMC2)

      ECB: Electronically Controlled Brake System

      HINT: 

      The Active Test can be performed when the following conditions are met.

      • ABS main relay is on.
      • Shift position is in P.
      • Parking brake is applied.
      • Vehicle speed is 0 km/h (0 mph).
    2. Perform the Active Test of the solenoid using the Techstream.
    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
      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 > Data List 

      Tester Display
      FL W/C Sensor
    4. Check that the output value of the wheel cylinder pressure sensor does not increase.

      OK

      The output value of the wheel cylinder pressure sensor does not increase.

      HINT: 

      If output value increases, there may be brake fluid leaks in the brake actuator assembly.

      Result

      Result Proceed to
      The output values of the wheel cylinder pressure sensors do not increase. A
      The output value of the wheel cylinder pressure sensor increases. B

    Result: 

    B 

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

    Result: 

    A 

    See step  8

  8. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Select the Active Test on the Techstream.

      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 Solenoid (SLRRR) Linear solenoid (RRR) valve Valve close ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Solenoid (SLRRR)

      ECB: Electronically Controlled Brake System

      HINT: 

      The Active Test can be performed when the following conditions are met.

      • ABS main relay is on.
      • Shift position is in P.
      • Parking brake is applied.
      • Vehicle speed is 0 km/h (0 mph).
    2. Perform the Active Test of the solenoid using the Techstream.
    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
      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

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      RR W/C Sensor
    4. Check that the output value of the wheel cylinder pressure sensor does not increase.

      OK

      The output value of the wheel cylinder pressure sensor does not increase.

      HINT: 

      If output value increases, there may be brake fluid leaks in the brake actuator assembly.

      Result

      Result Proceed to
      The output values of the wheel cylinder pressure sensors do not increase. A
      The output value of the wheel cylinder pressure sensor increases. B

    Result: 

    B 

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

    Result: 

    A 

    See step  9

  9. PERFORM ACTIVE TEST USING TECHSTREAM (SOLENOID VALVE) 
    1. Select the Active Test on the Techstream.

      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 Solenoid (SLRRL) Linear solenoid (RLR) valve Valve close ON/OFF ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Solenoid (SLRRL)

      ECB: Electronically Controlled Brake System

      HINT: 

      The Active Test can be performed when the following conditions are met.

      • ABS main relay is on.
      • Shift position is in P.
      • Parking brake is applied.
      • Vehicle speed is 0 km/h (0 mph).
    2. Perform the Active Test of the solenoid using the Techstream.
    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
      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
      RL W/C Sensor
    4. Check that the output value of the wheel cylinder pressure sensor does not increase.

      OK

      The output value of the wheel cylinder pressure sensor does not increase.

      HINT: 

      If output value increases, there may be brake fluid leaks in the brake actuator assembly.

      Result

      Result Proceed to
      The output values of the wheel cylinder pressure sensors do not increase. A
      The output value of the wheel cylinder pressure sensor increases. B

    Result: 

    A 

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    B 

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

  10. INSPECT ABS MOTOR RELAY 
    1. Remove the ABS motor relay (ABS MTR NO. 1 and ABS MTR NO. 2 relays).
      GTY803003Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 ABS Motor Relay (ABS MTR NO. 1 or ABS MTR NO. 2 relay)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      3 - 5 Voltage is not applied between terminals 1 and 2 10 kΩ or higher
      3 - 5 Voltage is applied between terminals 1 and 2 Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE ABS MOTOR RELAY 

    Result: 

    OK 

    See step  11

  11. INSPECT NO. 1 ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK (POWER SOURCE TERMINAL) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      ABS MTR NO. 1 relay terminal 5 - Body ground Always 11 to 14 V
      ABS MTR NO. 2 relay terminal 5 - Body ground Always 11 to 14 V
      GTY791530Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 NO. 1 Engine Room Relay Block and Junction Block
      *2 ABS MTR NO. 1 Relay
      *3 ABS MTR NO. 2 Relay

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT) 

    Result: 

    OK 

    See step  12

  12. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY - NO. 1 ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.
    2. Disconnect the A48 and A49 brake booster with accumulator pump assembly connectors.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A48-2 (BM1) - ABS MTR NO. 1 relay terminal 3 Always Below 1 Ω
      A48-2 (BM1) or ABS MTR NO. 1 relay terminal 3 - Body ground Always 10 kΩ or higher
      A49-2 (BM2) - ABS MTR NO. 2 relay terminal 3 Always Below 1 Ω
      A49-2 (BM2) or ABS MTR NO. 2 relay terminal 3 - 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 (SKID CONTROL ECU ASSEMBLY - NO. 1 ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connectors.
    2. Disconnect the A11 and A8 skid control ECU assembly connectors.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A8-24 (R1-) - ABS MTR NO. 1 relay terminal 2 Always Below 1 Ω
      A8-24 (R1-) or ABS MTR NO. 1 relay terminal 2 - Body ground Always 10 kΩ or higher
      A8-11 (MR1) - ABS MTR NO. 1 relay terminal 1 Always Below 1 Ω
      A8-11 (MR1) or ABS MTR NO. 1 relay terminal 1 - Body ground Always 10 kΩ or higher
      A11-14 (R2-) - ABS MTR NO. 2 relay terminal 2 Always Below 1 Ω
      A11-14 (R2-) or ABS MTR NO. 2 relay terminal 2 - Body ground Always 10 kΩ or higher
      A11-17 (MR2) - ABS MTR NO. 2 relay terminal 1 Always Below 1 Ω
      A11-17 (MR2) or ABS MTR NO. 2 relay terminal 1 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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