CAN COMMUNICATION SYSTEM Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus lines

  • Central gateway ECU (network gateway ECU)

  • ECM

  • No. 2 CAN junction connector

  • No. 4 CAN junction connector

WIRING DIAGRAM

B006YVIE03

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

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 ignition 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 (-) 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

  • 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 and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes 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.

    Click here

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 SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the A67 No. 2 CAN junction connector.

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

      B007124C11
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to No. 4 CAN Junction Connector
      *c to ECM - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A67-10 (CANH) - A67-21 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 4 CAN junction connector
      A67-11 (CANH) - A67-22 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      Result
      Result Proceed to
      OK A
      NG (Line to ECM) B
      NG (Line to No. 4 CAN junction connector) C

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR) Click here

    B

  2. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - ECM)


    1. Disconnect the A22, A23 or A24 ECM connector.

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

      B007124C12
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to ECM
      Standard Resistance
      Tester Connection Condition Specified Condition
      A67-11 (CANH) - A67-22 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result Proceed to
      OK (for A25A-FKS) A
      OK (for 2GR-FKS) B
      OK (for 2AR-FE) C
      NG D

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here

    D

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

  3. CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)


    1. Disconnect the K128 No. 4 CAN junction connector.

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

      B006ZE9C35
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to No. 2 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K128-11 (CANH) - K128-22 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher No. 2 CAN junction connector
      Result
      Result
      OK
      NG

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

    OK

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


    1. Disconnect the K127 No. 4 CAN junction connector.

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

      B007124C09
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K127-1 (CANH) - K127-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      Result
      Result
      OK
      NG

    OK

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    NG

  5. CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the K76 central gateway ECU (network gateway ECU) connector.

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

      B007124C09
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition
      K127-1 (CANH) - K127-12 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))