ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1378/44

DTC Code DTC Name
C1378/44 Capacitor Communication Malfunction

DESCRIPTION

The brake control power supply (capacitor) provides auxiliary power for brake control when the auxiliary battery (12 V) voltage drops.

The FAIL and ENA lines are placed between the skid control ECU and the brake control power supply.

Signals indicating that the brake control power supply is in auxiliary mode are sent to the skid control ECU through the FAIL line.

Charge permit prohibition signals are sent to the brake control power supply through the ENA line.

DTC Code INF Code DTC Detection Condition Trouble Area
C1378/44 112

Any of the following is detected:


  1. Open or short in FAIL line.

  2. Malfunction inside the power back up unit.

  3. IG1 terminal voltage is 9.5 V or more, and condition that capacitor communication is malfunctioning continues for 12 seconds or more.

  • Brake control power supply

  • Brake control power supply circuit

WIRING DIAGRAM

Refer to DTC C1377/43 Click here.

INSPECTION PROCEDURE

Note

When replacing the skid control ECU, perform initialization and calibration of the linear solenoid valve Click here.

PROCEDURE


  1. INSPECT BRAKE CONTROL POWER SUPPLY (IG1 TERMINAL)


    1. A01NGIYE11
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Brake Control Power Supply)

      Make sure that there is no looseness at the locking part and the connecting part of the connector.

    2. Disconnect the brake control power supply connector.

    3. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      P47-5 (IG1) - Body ground Power switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  2. INSPECT BRAKE CONTROL POWER SUPPLY (GND TERMINAL)


    1. A01NGIYE10
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Brake Control Power Supply)

      Turn the power switch off.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      P47-14 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

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


    1. A01NFRNE02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Skid Control ECU)
      *2

      Front view of wire harness connector

      (to Brake Control Power Supply)

      Make sure that there is no looseness at the locking part and the connecting part of the connector.

    2. Disconnect the skid control ECU connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A90-20 (ENA) - P47-12 (ENA) Always Below 1 Ω
      A90-20 (ENA) - Body ground Always 10 kΩ or higher
      A91-30 (FAIL) - P47-13 (FAIL) Always Below 1 Ω
      A91-30 (FAIL) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. RECONFIRM DTC


    1. Reconnect the skid control ECU connectors and the brake control power supply connector.

    2. Clear the DTCs Click here.

    3. Turn the power switch on (IG).

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

      Result
      Result Proceed to
      DTC (C1378/44) is output A
      DTC (C1378/44) is not output B

    B

    CHECK FOR INTERMITTENT PROBLEMS Click here

    A

  5. CHECK FREEZE FRAME DATA


    1. Check the INF code from the Freeze Frame Data memorized when the DTC (C1378/44) is stored Click here.

      Result
      Result Proceed to
      INF code (112) is not output A
      INF code (112) is output B

    B

    REPLACE BRAKE CONTROL POWER SUPPLY Click here

    A

    REPLACE SKID CONTROL ECU Click here