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

  • Short in CAN branch lines

  • Central gateway ECU (network gateway ECU)

  • ECM

  • Engine stop and start ECU

    (w/ Stop and Start System)

  • No. 2 CAN junction connector

    (w/ Stop and Start System)

WIRING DIAGRAM


  1. w/o Stop and Start System

    B008K9DE01
    *1 Central Gateway ECU (Network Gateway ECU)

  2. w/ Stop and Start System

    B008L8VE02
    *a Engine Stop and Start ECU
    *b Central Gateway ECU (Network Gateway ECU)
    *c No. 2 CAN Junction Connector

CAUTION / NOTICE / HINT

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 blind spot monitor system on using the blind spot monitor main switch (ON/OFF switch), turn the cruise control main switch on, turn the LDA main switch on and then drive the vehicle at a speed of 60 km/h (37 mph) or more for approximately 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

  • Before replacing the ECM, refer to Service Bulletin.*1


  • *1: w/ Entry and Start System

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 VEHICLE TYPE


    1. Check vehicle type.

      Result
      Result Proceed to
      w/o Stop and Start System A
      w/ Stop and Start System B

    B

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

    A

  2. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


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

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

    3. B008KCJC05
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))
      *b to ECM

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F74-18 (CA4H) - F74-17 (CA4L) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    B

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    C

  3. CHECK FOR SHORT IN CAN BUS LINES (ECM - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the A38 ECM connector.

    2. B008KCJC05
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))
      *b to ECM

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F74-18 (CA4H) - F74-17 (CA4L) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result Proceed to
      OK (for 8NR-FTS) A
      OK (for 3ZR-FAE) B
      NG C

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


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

    2. Disconnect the No. 2 CAN junction connector.

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

      B008LF8C20
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c to ECM *d to Engine Stop and Start ECU
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F113-1 (CANH) - F113-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      F113-4 (CANH) - F113-15 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      F113-6 (CANH) - F113-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Engine stop and start ECU
      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to ECM) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    C

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

    D

    CHECK FOR SHORT IN CAN BUS LINES (ECU OR SENSOR) Click here

    B

  5. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the F74 central gateway ECU (network gateway ECU) connector.

    2. B008LN3C28
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)
      *b 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
      F113-1 (CANH) - F113-12 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    B

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


    1. Disconnect the A38 ECM connector.

    2. B008LN3C08
      *a

      Front view of wire harness connector

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F113-4 (CANH) - F113-15 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

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

  7. CHECK FOR SHORT IN CAN BUS LINES (ECU OR SENSOR)


    1. Reconnect all wire harness connectors.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

      Click here

    3. B008LCEC02
      *a

      Component with harness connected

      (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
      F74-18 (CA4H) - F74-17 (CA4L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

      Tech Tips


      • If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.

      • If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short in the wire harness and repair or replace the wire harness or connector if necessary.

      Result
      Result
      OK
      NG

    OK

    REPLACE ECU OR SENSOR

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR