CAN COMMUNICATION SYSTEM ECM Communication Stop Mode

DESCRIPTION

Detection Item Symptom Trouble Area
ECM Communication Stop Mode

Either condition is met:


  • Communication stop for "ECM (Engine)" is indicated on the "Communication Bus Check" screen of the GTS.

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

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  • ECM main line or connector

  • Power source circuit of ECM

  • ECM ground circuit

  • ECM

WIRING DIAGRAM

B003YKTE06
*a No. 2 CAN Junction Connector
*b from EFI MAIN Relay
*c from IG2 Relay
*d IGN NO. 1

CAUTION / NOTICE / HINT

Note


  • 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 or any 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 notices before proceeding with work.

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  • 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.

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

    DTC check procedure: Turn the power switch on (IG) and wait at least 20 seconds.

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

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

Tech Tips


  • Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.

  • When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE


  1. CHECK FOR OPEN IN CAN BUS LINES (ECM MAIN LINE)


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

    2. Disconnect the A78 ECM connector.

    3. B003XRUC11
      *a

      Front view of wire harness connector

      (to ECM)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A78-13 (CANH) - A78-26 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM)

    OK

  2. CHECK ECM POWER SOURCE CIRCUIT


    1. Check the ECM power source circuit.


      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)