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

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

DESCRIPTION

DTC No. Detection Item DTC Detection Condition Trouble Area DTC Output from
U0129 Lost Communication with Brake System Control Module No communication from the brake booster with master cylinder assembly (skid control ECU) continues.

  • Power source circuit of brake booster with master cylinder assembly (skid control ECU)

  • Brake booster with master cylinder assembly (skid control ECU) ground circuit

  • Brake booster with master cylinder assembly (skid control ECU) CAN branch wire or connector

  • Brake booster with master cylinder assembly (skid control ECU)

 Hybrid vehicle control ECU

WIRING DIAGRAM

A0001YVE03

CAUTION / NOTICE / HINT

Note


  • Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

    Click here

  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

    Click here

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed.

    Click here

  • DTC check procedure: Turn the power switch on (IG) and wait at least 13 seconds.

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

Tech Tips


  • Operating the power switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE


  1. RECONFIRM DTC OUTPUT


    1. Check for DTCs.


      Body Electrical > HV Gateway > Trouble Codes

      Tech Tips

      If the hybrid vehicle control ECU outputs DTC U0100 and DTC U0129, check the branch circuit of sub bus 15.

      Result
      Result Proceed to
      The hybrid vehicle control ECU outputs only DTC U0129. A
      The hybrid vehicle control ECU outputs DTC U0100 and U0129. B

    B

    GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

    A

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


    1. B002IX7C14
      *a

      Front view of wire harness connector

      (to Brake Booster with Master Cylinder Assembly [Skid Control ECU])

      Disconnect the cable from the negative (-) auxiliary battery terminal.

    2. Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A57-35 (CA2H) - A57-34 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

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


    1. A000061C18
      *a

      Front view of wire harness connector

      (to Brake Booster with Master Cylinder Assembly [Skid Control ECU])

      Reconnect the cable to the negative (-) auxiliary battery terminal.

      Note

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

      Click here

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A57-15 (BS) - Body ground Power switch off 11 to 14 V
      A57-14 (BI) - Body ground Power switch off 11 to 14 V
      A57-16 (IG1) - Body ground Power switch on (IG) 11 to 14 V
      A57-12 (IG2) - Body ground Power switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A57-28 (GND) - Body ground Always Below 1 Ω
      A57-27 (GND2) - Body ground Always Below 1 Ω
      A57-26 (GND3) - Body ground Always Below 1 Ω
      A57-25 (GND4) - Body ground Always Below 1 Ω
      A57-24 (GND5) - Body ground Always Below 1 Ω
      A57-23 (GND6) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR