SFI SYSTEM, Diagnostic DTC:U0129 and U1103

DTC Code DTC Name
U0129 Lost Communication with Skid Control ECU
U1103 Lost Communication with Stop and Start Control Module

DESCRIPTION

The ECM, brake actuator assembly (skid control ECU assembly) and engine stop and start ECU communicate with each other via CAN communication. Each ECUs also communicate with other computers through the ECM. If there is a problem with this communication, the ECM stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

U0129

Lost Communication with Skid Control ECU

All of the following conditions are met for 0.7 seconds (1 trip detection logic):

  • Ignition switch ON

  • Battery voltage 10 V or higher

  • No communication between ECM and skid control ECU

  • Brake actuator assembly (Skid control ECU assembly)

  • CAN communication system

  • ECM

Comes on

DTC stored

U1103

Lost Communication with Stop and Start Control Module

Both of the following conditions are met for 0.76 seconds (1 trip detection logic):

  • Ignition switch ON

  • Battery voltage 10 V or higher

  • No communication between ECM and stop and start ECU

  • Wire harness (CANL and CANH circuits)

  • ECM

  • Engine stop and start ECU

Comes on

DTC stored (w/ stop and start system)

- (w/o stop and start system)

WIRING DIAGRAM

A327736E01

CONFIRMATION DRIVING PATTERN

  • DTC U0129 is detected when the ignition switch is ON and wait for 3 seconds.

  • DTC U1103 is detected when the ignition switch is ON and wait for 2 seconds.

CAUTION / NOTICE / HINT

Tip:

  • When DTCs indicating a CAN communication system malfunction are output, repair the CAN communication system first.

  • Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

  • If the CAN communication system is malfunctioning, there is no data output from the ECM. In this case, some of the freeze frame data will not be correct and not identical with the ECM data, but the ECM data are correct.

PROCEDURE

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC U0129 OR U1103)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: System Select / Health Check.

    5. Read the DTCs.

      Result

      Result

      Proceed to

      DTC U0129 or U1103 is output

      A

      DTC U0129 or U1103 and other DTCs are output

      B
      Tip:

      If any DTCs other than U0129 or U1103 are output, troubleshoot those DTCs first.

    A

    GO TO CAN COMMUNICATION SYSTEM FOR TROUBLESHOOTING

    Click hereClick here

    B

    GO TO DTC CHART