ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1377/43

DTC Code DTC Name
C1377/43 Capacitor Malfunction

DESCRIPTION

The brake control power supply (capacitor) is used as auxiliary power for brake control when battery voltage is low.

DTC Code Information Code DTC Detection Condition Trouble Area
C1377/43 101

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Brake control power supply is deteriorated (indicates a need to replace).

 Brake control power supply
↑ 102

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Self-discharge (current leak) is excessive (internal malfunction).

 ↑
↑ 103

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Overvoltage (16.4 V or more) continues to be applied from the battery to the brake control power supply voltage input (+BC) for 10 seconds or more.

 Positive battery circuit (Apply high voltage)
↑ 105

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Circuit inside the power back up unit (charge) is malfunctioning.

 Brake control power supply
↑ 106

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Circuit inside the power back up unit (back up output circuit) is malfunctioning.

 ↑
↑ 108

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Circuit inside the power back up unit (voltage monitor circuit) is malfunctioning.

 ↑
↑ 109

When both conditions below are met:


  • IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  • Open circuit between battery (12 V) and brake control power supply power input (+BC terminal).

  • ABS MAIN4 fuse

  • Harness or connector
↑ 110

When both conditions below are met:


  1. IG1 terminal voltage is 9.5 V or more, and malfunction signal (not capacitor communication malfunction) reception condition continues for 3 seconds or more

  2. When either of the following is detected:


    • Open or short circuit between battery (12 V) and brake control power supply output 1 (OUT1).

    • Open or short circuit between battery (12 V) and brake control power supply output 2 (OUT2).

  • ABS MAIN4 fuse

  • Harness or connector

WIRING DIAGRAM

A000W59E07

PROCEDURE


  1. CHECK FREEZE FRAME DATA


    1. Check the information code from the "FREEZE FRAME DATA" memorized when the DTC (C1377/43) is stored Click here.

      Result
      Result Proceed to
      Information codes (109 and 110) are output A
      Information codes (101, 102, 105, 106 and 108) are output B
      Information code (103) is output C

    B

    REPLACE BRAKE CONTROL POWER SUPPLY ASSEMBLY Click here

    C

    INSPECT BATTERY Click here

    A

  2. INSPECT FUSE (ABS MAIN4)


    1. Remove the ABS MAIN4 fuse from the luggage room junction block.

    2. Measure the resistance of the fuse.

      Standard resistance
      Tester Connection Condition Specified Condition
      ABS MAIN4 fuse Always Below 1 Ω

    NG

    REPLACE FUSE

    OK

  3. CHECK TERMINAL VOLTAGE AND RESISTANCE (+BC, GND)


    1. A000XKOE01
      *1 Rear view of wire harness connector: (to Brake Control Power Supply Assembly)

      Disconnect the R72 power supply connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      R72-8 (+BC) - Body ground Always 11 to 14 V

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

      Standard resistance
      Tester Connection Condition Specified Condition
      R72-14 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT BRAKE CONTROL POWER SUPPLY ASSEMBLY (OUT1, OUT2)


    1. A000W6RE01
      *1 Component with harness connected: (Brake Control Power Supply Assembly)

      Connect the R72 power supply connector.

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

      Tech Tips

      Perform inspection while the brake is not operated.

      Standard voltage
      Tester Connection Condition Specified Condition
      R72-1 (OUT1) - Body ground While the brake is not operated 11 to 14 V
      R72-7 (OUT2) - Body ground While the brake is not operated 11 to 14 V
      Result
      Result Proceed to
      NG A
      OK B

    B

    RECONFIRM DTC Click here

    A

  5. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE CONTROL POWER SUPPLY)


    1. Disconnect the A19 and A21 ECU connectors.

    2. Disconnect the R72 power supply connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A19-38 (CBI1) - R72-1 (OUT1) Always Below 1 Ω
      A21-40 (CBI2) - R72-7 (OUT2) Always Below 1 Ω
      A19-38 (CBI1) - Body ground Always 10 kΩ or higher
      A21-40 (CBI2) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      NG A
      OK B

    A

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    B

    RECONFIRM DTC Click here

  6. INSPECT BATTERY


    1. Check the battery voltage.

      Standard voltage
      11 to 14 V

    NG

    RECHARGE OR REPLACE BATTERY Click here

    OK

  7. INSPECT BRAKE CONTROL POWER SUPPLY ASSEMBLY (+BC TERMINAL)


    1. A000ZIDE01
      *1 Rear view of wire harness connector: (to Brake Control Power Supply Assembly)

      Disconnect the R72 power supply connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      R72-8 (+BC) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (+BC CIRCUIT)

    OK

  8. RECONFIRM DTC


    1. Clear the DTC Click here.

    2. Turn the power switch ON (IG).

    3. Check if the same DTC is recorded Click here.

      Tech Tips

      Reinstall the sensors, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

      Result
      Result Proceed to
      DTC (C1377/43) is not output A
      DTC (C1377/43) is output B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE CONTROL POWER SUPPLY ASSEMBLY Click here