ELECTRONICALLY CONTROLLED BRAKE SYSTEM, Diagnostic DTC:C1378

DTC Code DTC Name
C1378 Capacitor Communication Malfunction

DESCRIPTION

The brake control power supply with bracket assembly 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 with bracket assembly.

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

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

DTC No. Detection Item INF Code DTC Detection Condition Trouble Area Note
C1378 Capacitor Communication Malfunction 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 brake control power supply with bracket assembly communication malfunction continues for 12 seconds or more.

  • Wire harness and connector

  • Improperly connected connector, deformation or corrosion of terminals

  • Brake control power supply with bracket assembly

 -
DTC Detection Conditions: C1378 INF Code: 112
Vehicle Condition
Pattern 1 Pattern 2 Pattern 3 Pattern 4
Diagnosis Condition IG1 terminal voltage is 9.5 V or more - - ○ ○
Malfunction Status Open or short in FAIL line ○ - - -
Malfunction inside the power back up unit - ○ - -
A malfunction signal is received from the brake control power supply with bracket assembly - - ○ -
Communication from the brake control power supply with bracket assembly is invalid (normal signals, capacitor mode signals or malfunction signals cannot be received) - - - ○
Detection Time - - 12 seconds or more 12 seconds or more
Number of Trips 1 trip 1 trip 1 trip 1 trip

WIRING DIAGRAM

Refer to DTC C1377.

Click here

CAUTION / NOTICE / HINT

Note


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

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)


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

    2. Disconnect the L101 brake control power supply with bracket 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 Condition Specified Condition
      L101-3 (IG1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  2. CHECK HARNESS AND CONNECTOR (GND TERMINAL)


    1. 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
      L101-8 (GND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

    OK

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


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

    2. Disconnect the A11 and A12 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
      A11-20 (ENA) - L101-2 (ENA) Always Below 1 Ω
      A11-20 (ENA) or L101-2 (ENA) - Body ground Always 10 kΩ or higher
      A12-30 (FAIL) - L101-7 (FAIL) Always Below 1 Ω
      A12-30 (FAIL) or L101-7 (FAIL) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. RECONFIRM DTC


    1. Reconnect the A11 and A12 skid control ECU assembly connectors.

    2. Reconnect the L101 brake control power supply with bracket assembly connector.

    3. Clear the DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    4. Turn the power switch off.

    5. Turn the power switch on (IG).

    6. Check if the same DTC is output.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      DTC C1378 is output. A
      DTC C1378 is not output. B

    B

    USE SIMULATION METHOD TO CHECK Click here

    A

  5. CHECK FREEZE FRAME DATA


    1. Check the INF code from the Freeze Frame Data stored when DTC (C1378) was stored.

      Click here


      Chassis > ABS/VSC/TRC > DTC(C1378) > Freeze Frame Data
      Tester Display
      Detailed Freeze DTC
      Result
      Result Proceed to
      INF code 112 is output. A
      INF code 112 is not output. B

    A

    REPLACE BRAKE CONTROL POWER SUPPLY WITH BRACKET ASSEMBLY Click here

    B

    REPLACE SKID CONTROL ECU ASSEMBLY for LHD: Click here
    REPLACE SKID CONTROL ECU ASSEMBLY for RHD: Click here