CAN COMMUNICATION SYSTEM Open in Bus 2 Main Bus Line

DESCRIPTION

There may be an open circuit in one of the CAN main bus lines and/or a central gateway ECU (network gateway ECU) branch line when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.

Symptom Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.

  • CAN main bus lines or connector

  • Central gateway ECU (network gateway ECU) branch lines or connector

  • ECM

  • Combination meter assembly

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

This malfunction is not related to the lines of a CAN branch except the central gateway ECU (network gateway ECU) branch lines or to ECUs or sensors connected to a CAN branch.

WIRING DIAGRAM

Figure 1. for LHD

B003XXEE05
*a Central Gateway ECU (Network Gateway ECU)
*b No. 1 CAN Junction Connector
*c Combination Meter Assembly
*d No. 2 CAN Junction Connector

Figure 2. for RHD

B003XXEE06
*a Central Gateway ECU (Network Gateway ECU)
*b No. 2 CAN Junction Connector
*c No. 1 CAN Junction Connector
*d Combination Meter Assembly

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 60 seconds. Turn the cruise control main switch on, turn the lane departure alert main switch on and then drive the vehicle at a speed of 36 km/h (22 mph) or more for 52 seconds or more.

  • 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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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 (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) BRANCH LINE)


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

    2. Disconnect the K146 central gateway ECU (network gateway ECU) connector.

    3. B003YK5C23
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K146-18 (CA4H) - K146-17 (CA4L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

      Note

      When the measured value is 133 Ω or higher and a CAN communication system DTC is output, there may be a fault besides disconnection of the central gateway ECU (network gateway ECU) branch line. For that reason, troubleshooting should be performed again from How to Proceed with Troubleshooting after repairing the trouble area.

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      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE CAN BRANCH LINES CONNECTED TO CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

    OK

  2. CHECK FOR OPEN IN CAN BUS LINES (COMBINATION METER ASSEMBLY)


    1. Disconnect the K3 combination meter assembly connector.

    2. B003YEAC21
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K3-29 (CANH) - K3-30 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

  3. CHECK FOR OPEN IN CAN BUS LINES (ECM)


    1. Reconnect the K3 combination meter assembly connector.

    2. Disconnect the A78 ECM connector.

    3. B003XRUC12
      *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

    OK

    REPLACE ECM Click here

    NG

  4. CHECK FOR OPEN IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the A78 ECM connector.

    2. Disconnect the K109 No. 1 CAN junction connector.

    3. B003YNBC41
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)
      *b to No. 2 CAN Junction Connector
      *c to Combination Meter Assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K109-1 (CANH) - K109-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 2 CAN junction connector
      K109-2 (CANH) - K109-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Combination meter assembly
      Result
      Result Proceed to
      OK A
      NG (Line to Combination meter assembly) B
      NG (Line to No. 2 CAN junction connector) C

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)

    C

  5. CHECK FOR OPEN IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the K109 No. 1 CAN junction connector.

    2. Disconnect the K110 No. 2 CAN junction connector.

    3. B003YNBC42
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)
      *b to No. 1 CAN Junction Connector
      *c to ECM

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K110-1 (CANH) - K110-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 1 CAN junction connector
      K110-3 (CANH) - K110-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM
      Result
      Result Proceed to
      OK A
      NG (Line to ECM) B
      NG (Line to No. 1 CAN junction connector) C

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM - NO. 2 CAN JUNCTION CONNECTOR)

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)