CAN COMMUNICATION SYSTEM, Diagnostic DTC:U0129

DTC Code DTC Name
U0129 Lost Communication with Skid Control ECU

DESCRIPTION

DTC No. Detection Item DTC Detection Condition Trouble Area Note
U0129 Lost Communication with Skid Control ECU No communication from the skid control ECU (brake actuator assembly) continues.

  • Skid control ECU (brake actuator assembly) branch line or connector

  • Power source circuit of skid control ECU (brake actuator assembly)

  • Skid control ECU (brake actuator assembly) ground circuit

  • Skid control ECU (brake actuator assembly)

Tech Tips

The network gateway ECU stores DTCs when it detects a communication stop or network communication error for ECUs connected to sub bus 19.

Tech Tips

This diagnostic procedure is for when DTC U0129 is output by the network gateway ECU (GTS display: Gateway).

WIRING DIAGRAM

B0075RTE02
B0075RTE03

CAUTION / NOTICE / HINT

Note


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

  • After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) 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 performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • DTC check procedure: Turn the engine switch on (IG) and wait at least 60 seconds.

  • 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

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

Tech Tips


  • Operating the engine 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


    Body Electrical > Gateway > Trouble Codes

    1. Reconfirm DTCs.

      Tech Tips

      If DTC U1002 is output from Gateway of the network gateway ECU, this indicates a sub bus 19 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 19.

      Result
      Result Proceed to
      DTC U1002 is not output from network gateway ECU (GTS display: Gateway) A
      DTC U1002 is output from network gateway ECU (GTS display: Gateway) B

    B

    GO TO DIAGNOSTIC PROCEDURE INDICATED BY OUTPUT DTC Click here

    A

  2. CHECK FOR OPEN IN SUB BUS 19 BUS LINES (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) BRANCH LINE)


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

    2. B0077CFC01
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Disconnect the A15 skid control ECU (brake actuator assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A15-15 (CA2H) - A15-3 (CA2L) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY))

    OK

  3. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. B0077CFC02
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A15-1 (GND1) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω
      A15-13 (GND2) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω

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

    3. B0077CFC03
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A15-34 (IG1) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Result
      OK
      NG

    OK

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)