CAN COMMUNICATION SYSTEM 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 "CAN Bus Check" screen of the Techstream Click here

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


  • Power source circuit of ECM

  • ECM main line or connector

  • ECM ground circuit

  • ECM

WIRING DIAGRAM

A01HN4AE03

INSPECTION PROCEDURE

Note


  • Before measuring the resistance of the CAN bus, turn the ignition 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 (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work Click here.

  • 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.

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

  • DTC check procedure: Turn the ignition switch to ON, turn the blind spot monitor system on using the blind spot monitor main switch (ON/OFF switch), wait at least 11.84 seconds and then drive the vehicle at a speed of 20 km/h (12 mph) or more for 5 minutes or more. Check that the warning light remains off after turning off following the initial light check.

  • After the repair, perform the 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 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 LINES (ECM MAIN LINE)


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

    2. A01HP37E09
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A25-13 (CANH) - A25-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

    NG
    OK
  2. CHECK ECM POWER SOURCE CIRCUIT


    1. Check the ECM power source circuit.

      for 2GR-FE: Click here

      for 2AR-FE: Click here

      Result
      Result Proceed to
      OK (for 2GR-FE) A
      OK (for 2AR-FE) B
      NG C

    B
    C
    A