CAN COMMUNICATION SYSTEM (for RHD), Diagnostic DTC:U0100

DTC Code DTC Name
U0100 Lost Communication with ECM / PCM "A"

DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U0100 There is no communication from the ECM.

  • Power source or inside of ECM

  • ECM CAN main wire or connector

  • ECM

WIRING DIAGRAM

A01FUAME05

INSPECTION PROCEDURE

Note


  • 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.

  • 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 notice before proceeding with work Click here.

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

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • DTC check procedure: Drive the vehicle for 3.5 seconds or more at a speed of 60 km/h (36 mph) or more.

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

Tech Tips


  • Operating the power switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • 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. Reconfirm DTCs.

      Tech Tips

      If DTC U1107-436 is output from Gateway of the power management control ECU, this indicates a sub bus 15 malfunction. Troubleshoot for DTC U1107-436 and check for malfunctions in sub bus 15.

      Result
      Result Proceed to
      DTC U1107-436 is not output from power management control ECU. A
      DTC U1107-436 is output from power management control ECU. B

    B

    GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

    A

  2. CHECK FOR OPEN IN CAN BUS WIRE (ECM CAN MAIN WIRE)


    1. A01FRO7E04
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

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

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A20-12 (CANP) - A20-25 (CANN) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    NG

    REPAIR OR REPLACE ECM CAN MAIN WIRE OR CONNECTOR (CANP, CANN)

    OK

  3. CHECK HARNESS AND CONNECTOR (ECM - BATTERY AND BODY GROUND)


    1. Connect the cable to the negative (-) auxiliary battery terminal.

      A01FU1JE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      		 - -

      Note

      When connecting the cable, some systems need to be initialized after the cable is reconnected Click here.

    2. Disconnect the ECM connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A20-1 (BATT) - Body ground Always 11 to 14 V
      A20-3 (+B2) - Body ground Auxiliary battery positive (+) voltage applied to terminal A20-46 (MREL) 11 to 14 V
      A20-2 (+B) - Body ground Auxiliary battery positive (+) voltage applied to terminal A20-46 (MREL) 11 to 14 V
      A20-32 (IGSW) - Body ground Power switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A20-14 (EC) - Body ground Always Below 1 Ω
      F5-24 (E02) - Body ground Always Below 1 Ω
      F5-25 (E01) - Body ground Always Below 1 Ω
      F4-49 (E1) - Body ground Always Below 1 Ω
      F5-59 (ME01) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here