CAN COMMUNICATION SYSTEM (for RHD), Diagnostic DTC:U0129

DTC Code DTC Name
U0129 Lost Communication with Brake System Control Module

DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U0129 There is no communication from the master cylinder solenoid (skid control ECU).

  • Power source circuit of master cylinder solenoid (skid control ECU)

  • Master cylinder solenoid (skid control ECU) CAN branch wire or connector

  • Master cylinder solenoid (skid control ECU)

WIRING DIAGRAM

A0156DCE03

INSPECTION PROCEDURE

Note

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

Tech Tips

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

PROCEDURE


  1. PRECAUTION

    Note

    After turning the ignition switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.


    NEXT

  2. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL


    1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the CAN main wire and the CAN branch wire.

      CAUTION:

      For vehicles with an SRS system:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

      Note

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.


    NEXT

  3. CHECK FOR OPEN IN CAN BUS WIRE (SKID CONTROL ECU CAN BRANCH WIRE)


    1. A015BY2E03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Master Cylinder Solenoid [Skid Control ECU])

      Disconnect the A24 master cylinder solenoid (skid control ECU) connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A24-11 (CANH) - A24-25 (CANL) Ignition switch off 54 to 69 Ω

    NG

    REPAIR OR REPLACE SKID CONTROL ECU CAN BRANCH WIRE OR CONNECTOR (CANH, CANL)

    OK

  4. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BATTERY AND BODY GROUND)


    1. A0155BIE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Master Cylinder Solenoid [Skid Control ECU])

      Connect the cable to the negative (-) battery terminal.

      Note

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.

    2. Disconnect the A25 master cylinder solenoid (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A24-2 (+BM1) - Body ground Always 11 to 14 V
      A24-31 (+BS) - Body ground Always 11 to 14 V
      A25-2 (+BM2) - Body ground Always 11 to 14 V
      A24-46 (IG1) - Body ground Ignition switch ON 11 to 14 V
      A25-1 (IG2) - Body ground Ignition switch ON 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A24-1 (GND1) - Body ground Always Below 1 Ω
      A24-32 (GND2) - Body ground Always Below 1 Ω
      A25-4 (GND3) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here