SFI SYSTEM, Diagnostic DTC:U0129

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

DESCRIPTION

The Controller Area Network (CAN) is a serial data communication system for real time applications. This is a vehicle multiplex communication system which has a high communication speed (500 kbps) and a high level of ability to detect malfunctions. By pairing the CANH and CANL bus wires, the communication on the CAN is performed using the voltage differential between the wires.

DTC No. DTC Detection Condition Trouble Area
U0129

All of the following conditions are met for 2.22 seconds or more (1 trip detection logic):


  • (a) Ignition switch ON

  • (b) Battery voltage is 10.5 V or more

  • (c) No communication between ECM and skid control ECU

  • Wire harness (CANL and CANH circuit)

  • ECM

  • Skid control ECU

  • CAN communication system

CAUTION / NOTICE / HINT

Tech Tips

Read freeze frame data using the GTS. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC U0129)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    5. Read DTCs.

      Result
      Result Proceed to
      DTC U0129 and other DTCs are output A
      DTC U0129 is output

      B*1

      C*2

      • *1: w/ Toyota Safety Sense

      • *2: w/o Toyota Safety Sense

      Tech Tips

      If any DTCs other than U10129 are output, troubleshoot those DTCs first.


    A

    GO TO DTC CHART Click here

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    C

    GO TO CAN COMMUNICATION SYSTEM Click here