CAN COMMUNICATION SYSTEM (for LHD) ECM Communication Stop Mode

DESCRIPTION

Detection Item Symptom Trouble Area
ECM Communication Stop Mode

Either Condition is met:


  • "ECM (Engine)" is not displayed on the "Bus Check" screen Click here.

  • Communication system DTCs (DTCs that start with U) that are output correspond to "ECM Communication Stop Mode" in "DTC Combination Table" Click here.

  • Power source circuit of ECM

  • ECM main line or connector

  • ECM ground circuit

  • ECM

WIRING DIAGRAM

A01FUAME03

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 auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the 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. CHECK FOR OPEN IN CAN BUS WIRE (ECM CAN MAIN WIRE)


    1. A01FRO7E03
      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
      A20-13 (CANH) - A20-26 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    NG

    REPAIR OR REPLACE ECM MAIN WIRE OR CONNECTOR (CANH, CANL)

    OK

  2. 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
      F5-49 (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