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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 135 (Electronically Controlled Brake System (HV) - Diagnostic Codes (09 Of 11)) >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for HV Model) >> DTC C141C-12: Brake Booster Motor "A" Control Circuit Short to Battery; DTC C141C-14: Brake Booster Motor "A" Control Circuit Short to Ground or Open; DTC C141C-1C: Brake Booster Motor "A" Control Circuit Voltage Out of Range [10/2021 - 11/2023] >> Procedure

DTC C141C-12: Brake Booster Motor "A" Control Circuit Short to Battery; DTC C141C-14: Brake Booster Motor "A" Control Circuit Short to Ground or Open; DTC C141C-1C: Brake Booster Motor "A" Control Circuit Voltage Out of Range [10/2021 - 11/2023]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK DTC 
    1. Check the DTCs that are output.

      Chassis > Brake Booster > Trouble Codes 

      Chassis > Brake/EPB > Trouble Codes 

      Result

      Result Proceed to
      DTCs C141C-12, C141C-14 and/or C141C-1C are output. A
      DTCs other than C141C-12, C141C-14 and C141C-1C are output. B

    Result: 

    B 

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS. Refer to  DIAGNOSTIC TROUBLE CODE CHART [10/2021 - 11/2023] 

    Result: 

    A 

    See step  2

  2. READ VALUE USING GTS (MOTOR RELAY) 
    1. Depress the brake pedal several times and check the operation status of the motor relay.

      Chassis > Brake Booster > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      ECB Motor Relay Motor relay operation request OFF / ON OFF: Relay off
      ON: Relay on      		 ECB: Electronically Controlled Brake System

      Chassis > Brake Booster > Data List 

      Tester Display
      ECB Motor Relay

      HINT: 

      Depressing the brake pedal several times drops the accumulator pressure and operates the pump motor.

      Result

      Result Proceed to
      The status of motor relay in the Data List turns on and off after depressing the brake pedal several times. A
      The status of motor relay in the Data List does not change even after depressing the brake pedal several times. B

    Result: 

    B 

    See step  10

    Result: 

    A 

    See step  3

  3. INSPECT BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY 
    1. Turn the ignition switch off.
      GTY883272Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Brake Booster with Accumulator Pump Assembly)
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    3. Disconnect the A9 brake booster with accumulator pump assembly connector.
    4. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (BM1) - 2 (GND1) Always 10 Ω or less

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER 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.

      OK

      The connector is securely connected.

    2. Disconnect the A44 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
    3. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A9-2 (GND1) - A44-30 (M-) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. READ VALUE USING GTS (ACCUMULATOR PRESSURE) 
    1. Reconnect the A9 brake booster with accumulator pump assembly connector.
    2. Reconnect the A44 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
    3. Disconnect the A43 brake pedal stroke sensor assembly connector.
    4. Depress the brake pedal several times to operate the pump motor, then wait until it stops.
    5. After the pump motor stops, wait for 30 seconds, then check the drop in the accumulator pressure sensor output value and the state of the pump motor.

      Chassis > Brake Booster > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      ECB Motor Relay Motor relay operation request OFF / ON OFF: Relay off
      ON: Relay on      		 ECB: Electronically Controlled Brake System
      Accumulator Pressure Accumulator pressure output value Min.: 0.00 MPa
      Max.: 24.48 MPa      		 15.00 to 21.00 MPa (Pressure stable and pump motor stopped) When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

      Chassis > Brake Booster > Data List 

      Tester Display
      ECB Motor Relay
      Accumulator Pressure

      HINT: 

      • This inspection checks whether an accumulator pressure sensor malfunction, internal brake booster with master cylinder assembly leak or prolonged operation due to detection of low pressure caused by accumulator deterioration, caused the DTC to be stored.
      • If the brake fluid level in the brake master cylinder reservoir assembly drops, an external brake fluid leak is suspected.

      Result

      Result Proceed to
      The drop in the accumulator pressure sensor output value is less than 2.50 MPa 30 seconds after the pump motor stops, and the pump motor does not operate within 30 seconds after the pump motor stops. A
      The drop in the accumulator pressure sensor output value is 2.50 MPa or more 30 seconds after the pump motor stops, or the pump motor operates within 30 seconds after the pump motor stops. B

    Result: 

    B 

    See step  8

    Result: 

    A 

    See step  6

  6. CLEAR DTC 
    1. Turn the ignition switch off.
    2. Reconnect the A43 brake pedal stroke sensor assembly connector.
    3. Clear the DTCs.

      Chassis > Brake Booster > Clear DTCs 

    4. Turn the ignition switch off.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  7

  7. RECONFIRM DTC 
    1. Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.
    2. Check if the same DTC is output.

      Chassis > Brake Booster > Trouble Codes 

      Result

      Result Proceed to
      DTCs C141C-12, C141C-14 and C141C-1C are not output. A
      DTCs C141C-12, C141C-14 and/or C141C-1C are output. B

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    B 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

  8. READ VALUE USING GTS (ACCUMULATOR PRESSURE) 
    1. Turn the ignition switch off.
    2. Reconnect the A43 brake pedal stroke sensor assembly connector.
    3. Drive the linear solenoid (SLA) by performing the Active Test to reduce the accumulator pressure.

      HINT: 

      Perform the Active Test with the current set to maximum.

    4. After reducing the accumulator pressure, confirm that the pump motor starts and the accumulator pressure returns to 15.00 to 21.00 MPa.

      Chassis > Brake Booster > Active Test 

      Tester Display Measurement Item Control Range Restrict Condition Diagnostic Note
      ECB Solenoid (SLA) Linear solenoid addition valve (SLA) Solenoid Start (Activate)
      Solenoid SLA
      (It is possible to set the current)      		 Vehicle condition:
      • Vehicle stopped
      • Shift lever is in P
      • Apply the parking brake
      		 ECB: Electronically Controlled Brake System

      Chassis > Brake Booster > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Accumulator Pressure Accumulator pressure output value Min.: 0.00 MPa
      Max.: 24.48 MPa      		 15.00 to 21.00 MPa (Pressure stable and pump motor stopped) When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator

      Chassis > Brake Booster > Active Test 

      Active Test Display
      ECB Solenoid (SLA)
      Data List Display
      Accumulator Pressure

      OK

      The accumulator pressure reduces, and then returns to 15.00 to 21.00 MPa when the pump motor operates.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    OK 

    See step  9

  9. RECONFIRM DTC 
    1. Confirm that the pump motor inside the brake booster with accumulator pump assembly is stopped.
    2. Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.
    3. Check if the same DTC is output.

      Chassis > Brake Booster > Trouble Codes 

      Result

      Result Proceed to
      DTCs C141C-12, C141C-14 and C141C-1C are not output. A
      DTCs C141C-12, C141C-14 and/or C141C-1C are output. B

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    B 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

  10. CHECK HARNESS AND CONNECTOR (MRI1 TERMINAL) 
    1. Turn the ignition switch off.
      GTY895228Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to No. 1 Skid Control ECU (Brake Booster with Master Cylinder Assembly))
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    3. Disconnect the A44 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
    4. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A44-1 (MRI1) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  11

  11. CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER 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.

      OK

      The connector is securely connected.

    2. Disconnect the A9 brake booster with accumulator pump assembly connector.
    3. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A44-29 (M+) - A9-1 (BM1) Always Below 1 Ω
      A44-29 (M+) or A9-1 (BM1) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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