ELECTRONICALLY CONTROLLED BRAKE SYSTEM(w/ Vacuum Brake Booster), Diagnostic DTC:C120B

DTC Code DTC Name
C120B IG Supply Voltage Low

DESCRIPTION

DTC No. Detection Item DTC Detection Condition Trouble Area Note
C120B IG Supply Voltage Low Master cylinder pressure sensor power supply voltage decrease occurs or history of voltage decrease exists, and defective master cylinder pressure sensor output continues for 1 second or more.

  • Master cylinder pressure sensor output defective

  • Skid control ECU (Brake actuator assembly)

  • VSC NO. 2 fuse

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WIRING DIAGRAM

Refer to DTC C1241.

Click here

CAUTION / NOTICE / HINT

Note


  • When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information.

    Click here

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (+BS TERMINAL)


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

    2. Disconnect the A9 skid control ECU (brake actuator assembly) connector.

    3. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A9-38 (+BS) - Body ground Always 11 to 14 V
      A9-38 (+BS) - A9-25 (GND1) Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

    OK

  2. RECONFIRM DTC


    1. Reconnect the A9 skid control ECU (brake actuator assembly) connector.

    2. Clear the DTCs.

      Click here


      Chassis > ABS/VSC/TRC > Clear DTCs

    3. Check if the same DTC is output.

      Click here


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      DTC C120B is not output. A
      DTC C120B is output. B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here