ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1378/44

DTC Code DTC Name
C1378/44 Capacitor Communication Malfunction

DESCRIPTION

The brake control power supply assembly (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 assembly and the brake control power supply assembly.

Signals indicating that the brake control power supply assembly 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 assembly 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 assembly

  • Brake control power supply circuit

WIRING DIAGRAM

Refer to DTC C1377/43 Click here.

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)


    1. A01FUGIE24
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Control Power Supply Assembly)

      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 assembly 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
      X1-5 (IG1) - Body ground Power switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  2. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


    1. A01FUGIE23
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Brake Control Power Supply Assembly)

      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
      X1-14 (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 ASSEMBLY - BRAKE CONTROL POWER SUPPLY ASSEMBLY)


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

    2. Disconnect the A14 and A16 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
      A14-8 (ENA) - X1-12 (ENA) Always Below 1 Ω
      A14-8 (ENA) - Body ground Always 10 kΩ or higher
      A16-41 (FAIL) - X1-13 (FAIL) Always Below 1 Ω
      A16-41 (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 assembly connectors and the brake control power supply assembly 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 ASSEMBLY Click here

    A

    REPLACE SKID CONTROL ECU ASSEMBLY Click here