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 wire

  • Short in CAN branch wire

  • Central gateway ECU (network gateway ECU)

  • Telematics transceiver*1

  • Bus buffer ECU*2

  • Radio receiver assembly

  • No. 9 CAN junction connector
*1: w/ Telematics Transceiver
*2: w/ Bus Buffer ECU

WIRING DIAGRAM

B005AUWE02

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 engine 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 engine 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

  • Some parts must be initialized and set when replacing or removing and installing parts.

    Click here

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

    DTC check procedure: Turn the engine switch on (IG) 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

  • The following malfunctions may occur if a radio receiver assembly from another vehicle is installed to this vehicle. Therefore, when replacing the radio receiver assembly, be sure to replace it with new one.


    • Communication malfunction DTC is output

    • Does not operate normally

Tech Tips


  • Operating the engine switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE


  1. CHECK FOR SHORT IN CAN BUS WIRES (NO. 9 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the No. 9 CAN junction connector.

    3. B005AFYC03
      *a

      Front view of wire harness connector

      (to No. 9 CAN Junction Connector)
      *b to Central Gateway ECU (Network Gateway ECU)
      *c to Radio Receiver Assembly
      *d to Telematics Transceiver (w/ Telematics Transceiver)
      *e to Bus Buffer ECU (w/ Bus Buffer ECU)
      *f 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 Connected to
      I166-1 (CANH) - I166-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      I166-2 (CANH) - I166-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio receiver assembly
      I166-3 (CANH) - I166-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Telematics transceiver*1
      I166-4 (CANH) - I166-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Bus buffer ECU*2
      I166-5 (CANH) - I166-16 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      *1: w/ Telematics Transceiver
      *2: w/ Bus Buffer ECU
      Result
      Result Proceed to
      OK A
      NG (Central gateway ECU [network gateway ECU] CAN main wire) B
      NG (Wire to ECU or sensor) C

    A

    REPLACE NO. 9 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR) Click here

    B

  2. CONNECT CONNECTOR


    1. Reconnect the I166 No. 9 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT

  3. CHECK FOR SHORT IN CAN BUS WIRES (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 9 CAN JUNCTION CONNECTOR)


    1. B0059GCC67
      *a

      Front view of wire harness connector

      (to Central Gateway ECU [Network Gateway ECU])

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I164-6 (CA3H) - I164-21 (CA3L) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I164-19 (CAYH) - I164-20 (CAYL)
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) for LHD: Click here
    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) for RHD: Click here

    NG

    REPLACE CAN BUS MAIN WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 9 CAN JUNCTION CONNECTOR)

  4. CHECK FOR SHORT IN CAN BUS WIRES (ECU, 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. B0058DHC14
      *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
      I164-6 (CA3H) - I164-21 (CA3L) 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.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECU OR SENSOR

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR