CAN COMMUNICATION SYSTEM Check CAN Bus Line for Short to GND (RHD Models)

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminals 6 (CANH) and 4 (CG) or 14 (CANL) and 4 (CG) of the DLC3.

Symptom Trouble Area
No resistance exists between terminals 6 (CANH) and 4 (CG) or 14 (CANL) and 4 (CG) of DLC3.

  • Short to ground in CAN main bus line

  • Short to ground in CAN branch line

  • ECM

  • Main body ECU (Multiplex network body ECU)

  • Combination meter assembly

  • Brake actuator assembly

  • Steering sensor

  • Clearance warning ECU assembly

  • Power steering ECU with motor assembly

  • Airbag sensor assembly

  • Air conditioning amplifier assembly

  • Smart key ECU assembly (Certification ECU)

  • Radio and display receiver assembly*

  • CAN No. 1 junction connector

  • CAN No. 2 junction connector

*: for Radio and Display Type

WIRING DIAGRAM

B000NIVE02
B000KUNE10

INSPECTION PROCEDURE

Note


  • 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.

  • 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.

  • 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, wait at least 31 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 5 minutes. Check that the warning light remains off after turning off following the initial light check.

  • After the repair, perform CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.

Tech Tips


  • Operating the ignition switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

  • 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.

  • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines. When the connectors have been disconnected from the CAN junction connector, reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wire harnesses, and to make future maintenance easier.

PROCEDURE


  1. CHECK FOR SHORT TO GND IN CAN BUS LINE (DLC3 BRANCH LINE)


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

    2. B000LXRE02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 2 Junction Connector)
      *b to DLC3

      Disconnect the DLC3 branch line connector (I96) from the CAN No. 2 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    OK

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE


    1. Reconnect the DLC3 branch line connector (I96) to the CAN No. 2 junction connector.

    2. B000J27E03
      Text in Illustration
      *1 DLC3

      Disconnect the connectors (I94, I95, I97, I100, I102, I103, I104, I105, I106, I07 and I111) from the CAN No. 1 junction connector and CAN No. 2 junction connector one at a time.

      Tech Tips

      Disconnect the ECU and sensor connectors other than the DLC3 branch lines and CAN main bus lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.

    3. Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 4 (CG), and between terminals 14 (CANL) and 4 (CG) of the DLC3 each time a connector is disconnected.

      B000HYBE02
      Text in Illustration
      *A for Radio and Display Type - -
      *1 Clearance Warning ECU Assembly *2 Steering Sensor
      *3 Brake Actuator Assembly *4 Smart Key ECU Assembly (Certification ECU)
      *5 DLC3 *6 Combination Meter Assembly
      *7 Radio and Display Receiver Assembly *8 ECM
      *9 Power Steering ECU with Motor Assembly *10 Airbag Sensor Assembly
      *11 Air Conditioning Amplifier Assembly *12 Main Body ECU (Multiplex Network Body ECU)
      *13 CAN No. 1 Junction Connector *14 CAN No. 2 Junction Connector
      B000MJ6E02
      Text in Illustration
      *a

      Component without harness connected

      (CAN No. 1 Junction Connector)

      		 - -
      Wiring Color
      CAN No. 1 Junction Connector Side Code Color (CANH Side) Color (CANL Side)
      Main body ECU (Multiplex network body ECU) I95 P W
      Air conditioning amplifier assembly I102 V W
      Airbag sensor assembly I103 Y W
      Power steering ECU with motor assembly I100 L W
      ECM I104 G W
      Radio and display receiver assembly* I107 R W
      CAN main bus line (bus line connecting CAN No. 1 junction connector and CAN No. 2 junction connector) I93 B W

      *: for Radio and Display Type

      B000GZZE02
      Text in Illustration
      *a

      Component without harness connected

      (CAN No. 2 Junction Connector)

      		 - -
      Wiring Color
      CAN No. 2 Junction Connector Side Code Color (CANH Side) Color (CANL Side)
      CAN main bus line (bus line connecting CAN No. 1 junction connector and CAN No. 2 junction connector) I101 B W
      Combination meter assembly I94 R W
      DLC3 I96 G W
      Smart key ECU assembly (Certification ECU) I106 L W
      Brake actuator assembly I105 Y W
      Steering sensor I97 V W
      Clearance warning ECU assembly I111 P W

      Note

      Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to GND in 2 or more CAN bus lines.

      Result
      Symptom Proceed to
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) is still below 200 Ω when all the specified connectors are disconnected from the CAN junction connector. (There is a short to GND in the CAN main bus lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.) A
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) becomes normal (200 Ω or higher) when a connector is disconnected from the CAN junction connector. (There is a short to GND in one of the areas that relate to the disconnected bus lines.) B

    4. When there is a short to GND in one or more of the bus lines that connect to an ECU or sensor:


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the bus line that is shorted to GND). Check that the resistance shown on the tester is normal (200 Ω or higher) to confirm that there is a short to GND in the one branch line only.

        Tech Tips


        • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

        • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wire harnesses, and to make future maintenance easier.

    5. When there is no short to GND in any of the bus lines that connect to the ECUs and sensors:


      1. With all the specified connectors for ECUs and sensors disconnected, proceed with the inspection of the CAN bus main lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.


    B

    CHECK FOR SHORT TO GND IN CAN BUS LINE (ECU, SENSOR) Click here

    A

  3. CHECK CAN NO. 2 JUNCTION CONNECTOR


    1. B000NHYE02
      Text in Illustration
      *a

      Rear view of wire harness connector

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

      Disconnect the CAN main bus line connector (I101) from the CAN No. 2 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    2. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

    OK

  4. CHECK CAN NO. 1 JUNCTION CONNECTOR


    1. Reconnect the CAN main bus line connector (I101) to the CAN No. 2 junction connector.

    2. B000J0ZE02
      Text in Illustration
      *a

      Rear view of wire harness connector

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

      Disconnect the CAN main bus line connector (I93) from the CAN No. 1 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

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

    OK

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

  5. CHECK FOR SHORT TO GND IN CAN BUS LINE (ECU, SENSOR)


    1. Reconnect the connector of the bus line that is shorted to GND to the CAN junction connector (the connector that caused the bus line resistance to change to 200 Ω or higher when it was disconnected).

    2. Disconnect the connector that includes the DLC3 connected CAN lines (such as CANH and CANL) from the ECU or sensor to which the bus line shorted to GND is connected Click here.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

      Tech Tips

      If the resistance changes to 200 Ω or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.


    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR