CAN COMMUNICATION SYSTEM Check Bus 3 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 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus lines

  • Short in CAN branch lines

  • Radio and display receiver assembly

    (for Radio and Display Type)

  • Central gateway ECU (network gateway ECU)

  • No. 4 CAN junction connector

WIRING DIAGRAM

A001R61E01

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 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.

    Click here

  • 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 approximately 30 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.

    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. 4 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the No. 4 CAN junction connector.

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

      A001NZ3C08
      *a

      Front view of wire harness connector

      (to No. 4 CAN junction connector)

      		 *b

      to Radio and Display Receiver Assembly

      (for Radio and Display Type)
      *c to Central Gateway ECU (Network Gateway ECU) - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F114-9 (CANH) - F114-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Radio and display receiver assembly*1
      F114-10 (CANH) - F114-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      F114-11 (CANH) - F114-22 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)

      • *1: for Radio and Display Type

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to ECU or sensor) C

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    C

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

    B

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


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

    2. A005MXMC10
      *a

      Front view of wire harness connector

      (to No. 4 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
      F114-10 (CANH) - F114-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher
      F114-11 (CANH) - F114-22 (CANL) Cable disconnected from negative (-) auxiliary 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. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

  3. 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. A001OOUC02
      *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
      F74-6 (CA3H) - F74-21 (CA3L) Cable disconnected from negative (-) auxiliary 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