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

DESCRIPTION

A short to GND is suspected in the CAN bus line when the resistance between terminals 4 (CG) and 6 (CANH), or terminals 4 (CG) and 14 (CANL) of the DLC3 is below 200 Ω.

Symptom Trouble Area
The resistance between terminals 6 (CANH) and 4 (CG), or terminals 14 (CANL) and 4 (CG) of the DLC3 is below 200 Ω.

Short to GND in CAN bus line


  • ECM

  • Skid control ECU (brake actuator assembly)

  • Distance control ECU*

  • Steering angle sensor

  • Yaw rate sensor

  • Power steering ECU

  • Seat belt control ECU*

  • Gateway ECU

  • Center airbag sensor

  • Multi-media module receiver assembly

WIRING DIAGRAM

A015ZFDE01
A0162NCE01

INSPECTION PROCEDURE

Note


  • Turn the engine switch off before measuring the resistance of CAN bus main wires and CAN bus branch wires.

  • After the engine switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.

  • Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the engine switch, any other switches, or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.

Tech Tips

Operating the engine switch, any switches, or any doors triggers related ECU and sensor communication with the CAN. This communication will cause the resistance value to change.

PROCEDURE


  1. CHECK FOR SHORT TO GND IN CAN BUS WIRE


    1. Turn the engine switch off.

    2. A0161BKE24

      Disconnect the J8 DLC3 branch line connector from the CAN LH junction connector B side (w/o earth terminal).

      Note


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

      • Reconnect the connector to its original position.

    3. A0161HNE26

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J21-6 (CANH) - J21-4 (CG) Engine switch off 200 Ω or higher
      J21-14 (CANL) - J21-4 (CG) Engine switch off 200 Ω or higher

    NG

    REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR

    OK

  2. RECONNECT CONNECTOR


    1. Reconnect the J8 DLC3 branch line connector to the CAN LH junction connector B side (w/o earth terminal).


    NEXT

  3. CHECK FOR SHORT TO GND IN CAN BUS WIRE


    1. A0161HNE26

      Disconnect connectors from the CAN LH junction connector and CAN RH 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 LH junction connector and CAN RH junction connector.

    2. 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.

      A0162IYE02
      A01622BE08
      Wiring Color
      CAN LH Junction Connector A Side (w/ Earth Terminal) Code Color (CANH Side) Color (CANL Side)
      Steering angle sensor J1 P W
      ECM J2 B W
      Seat belt control ECU* J3 V W
      Center airbag sensor J4 R W
      Wiring Color
      CAN LH Junction Connector B Side (w/o Earth Terminal) Code Color (CANH Side) Color (CANL Side)
      Yaw rate sensor J5 P W
      CAN main bus line (bus line connecting CAN LH junction connector and CAN RH junction connector) J7 B W
      DLC3 J8 G W
      Distance control ECU* J9 GR W
      Skid control ECU (brake actuator assembly) J128 R W

      • *: w/ Dynamic radar cruise control

      A015YKYE01
      Wiring Color
      CAN RH Junction Connector A Side (w/ Earth Terminal) Code Color (CANH Side) Color (CANL Side)
      CAN main bus line (bus line connecting CAN RH junction connector and CAN LH junction connector) J81 B W
      Power steering ECU J82 P W
      Wiring Color
      CAN RH Junction Connector B Side (w/o Earth Terminal) Code Color (CANH Side) Color (CANL Side)
      Gateway ECU J84 B W
      Multi-media module receiver assembly J116 SB 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 LH junction connector and CAN RH 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 more) 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

    3. 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 more) to confirm that there is a short to GND in the only one branch line.

        Tech Tips


        • The connectors connected to the CAN junction connector can be distinguished according to the color of the communication bus lines and the shape of the connectors.

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


    B

    RECONNECT CONNECTOR Click here

    A

    REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN LH JUNCTION CONNECTOR - CAN RH JUNCTION CONNECTOR)

  4. RECONNECT CONNECTOR


    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 more when it was disconnected).


    NEXT

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


    1. A0161HNE26

      Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the bus line shorted to GND is connected Click here.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J21-6 (CANH) - J21-4 (CG) Engine switch off 200 Ω or higher
      J21-14 (CANL) - J21-4 (CG) Engine switch off 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