CAN COMMUNICATION SYSTEM(w/o Toyota Safety Sense), Diagnostic DTC:U111A

DTC Code DTC Name
U111A Lost Communication with ECM/PCM "A" Powertrain Bus

DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U111A There is no communication from the ECM.

  • Power source of ECM

  • ECM

  • ECM main wire or connector

WIRING DIAGRAM

A01VFS8E02

CAUTION / NOTICE / HINT

Note


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

  • Turn the ignition switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.

  • Turn the ignition switch off before inspecting CAN bus wires for a ground short.

  • After the ignition switch is turned off, check that the key reminder warning system are not operating.

  • Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

Tech Tips


  • Operating the ignition 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. CHECK FOR OPEN IN CAN BUS WIRE (ECM MAIN WIRE)


    1. A01VDTBE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A58 ECM connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A58-12 (CANP) - A58-25 (CANN) Ignition switch off 108 to 132 Ω

    NG

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (ECM MAIN WIRE)

    OK

  2. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. A01VFLXE02
      Text in Illustration
      *A for LHD
      *B for RHD
      *a

      Front view of wire harness connector

      (to Stop and Start ECU)

      Disconnect the B22*1 or B23*2 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition

      B22-16 (E1) - Body ground*1

      B23-16 (E1) - Body ground*2

      		 Always Below 1 Ω

      • *1: for LHD

      • *2: for RHD

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A58-37 (IGSW) - Body ground Ignition switch ON 11 to 14 V
      A58-2 (+B) - Body ground Ignition switch ON 11 to 14 V
      A58-3 (+B2) - Body ground Ignition switch ON 11 to 14 V

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)