CAN COMMUNICATION SYSTEM Check CAN Bus Lines for Short Circuit (RHD Models)

DESCRIPTION

The CAN bus lines are considered to be shorted when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom Trouble Area
The resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Short in CAN bus lines


  • Skid control ECU

  • Steering angle sensor

  • Yaw rate sensor

  • ECM

  • Gateway ECU

  • Seat belt control ECU

  • Distance control ECU

  • Power steering ECU

  • Television camera ECU

  • Center airbag sensor

  • CAN LH junction connector

  • CAN RH junction connector

WIRING DIAGRAM

A016188E06
A015ZP0E04

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 in operation.

  • 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 IN CAN BUS WIRES (DLC3 BRANCH LINE)


    1. A016341E22

      Disconnect the DLC3 branch line connector (J94) from the CAN RH junction connector A side (w/ earth terminal).

      Note


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

      • Reconnect the connector to its original position.

    2. A0161HNE24

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 1 MΩ or higher

    NG

    REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR

    OK

  2. RECONNECT CONNECTOR


    1. Reconnect the DLC3 branch line connector (J94) to the CAN RH junction connector A side (w/ earth terminal).


    NEXT

  3. CHECK FOR SHORT IN CAN BUS WIRES (BRANCH LINE)


    1. A0161HNE24

      Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.

    2. While observing the resistance value shown on the tester, disconnect connectors J1, J3, J4, J6, J8, J82, and J97 from the CAN LH junction connector or CAN RH junction connector one by one until the resistance becomes normal (between 54 and 69 Ω).

      Tech Tips

      Disconnect the branch line connectors other than those of the DLC3.

      A0161TLE01
      A015Z7WE01
      Wiring Color
      CAN LH Junction Connector A Side (w/ Earth Terminal) Code Color (CANH Side) Color (CANL Side)
      Power steering ECU 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
      Skid control ECU J6 R W
      CAN main bus line (bus line connecting CAN LH junction connector and CAN RH junction connector) J7 B W
      Television camera ECU J8 L W
      A01609ME01
      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
      Steering angle sensor J82 P W
      DLC3 J94 G 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
      Distance control ECU J97 GR W

      Note

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

      Result
      Symptom Proceed to
      The resistance is still below 54 Ω when all the specified connectors are disconnected. (There are no shorts in the branch lines.) A
      The resistance becomes normal (between 54 and 69 Ω) when a connector is disconnected. (There is a short in one or more of the branch lines.) B

    3. When there is a short in one or more of the branch lines:


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the short-circuited bus line). Check that the resistance shown on the tester is normal (between 54 and 69 Ω) to confirm that there is a short 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

  4. CHECK FOR SHORT IN CAN BUS WIRES (GATEWAY ECU MAIN BUS LINE)


    1. A0161BKE23

      Disconnect the gateway ECU main bus line connector (J84) from the CAN RH 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.

    2. A0161HNE24

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 108 to 132 Ω
      Result
      Symptom Proceed to
      The resistance is still below 54 Ω when the gateway ECU connector is disconnected. (There are no shorts in the gateway ECU main bus lines.) A
      The resistance falls within the specified range (between 108 and 132 Ω) (either of the terminating resistances is normal) when the gateway ECU connector is disconnected. (There is a short in the gateway ECU main bus lines.) B

    B

    RECONNECT CONNECTOR Click here

    A

  5. CHECK FOR SHORT IN CAN BUS WIRES (ECM MAIN BUS LINE)


    1. A016341E20

      Disconnect the ECM main bus line connector (J2) from the CAN LH junction connector A side (w/ earth terminal) .

      Note


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

      • Reconnect the connector to its original position.

    2. A0161HNE24

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 1 MΩ or more

      Tech Tips

      Measure the resistance with the gateway ECU main bus line connector (J84) disconnected.

      Result
      Symptom Proceed to
      The resistance is still below 1 MΩ when the ECM connector is disconnected. (There are no shorts in the ECM main bus lines.) A
      The resistance becomes 1 MΩ or more when the ECM connector is disconnected. (There is a short in the ECM main bus lines.) B

    B

    RECONNECT CONNECTOR Click here

    A

  6. CHECK CAN RH JUNCTION CONNECTOR


    1. A016341E21

      Disconnect the CAN main bus line connector (J81) from the CAN RH junction connector A side (w/ earth terminal) .

      Note


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

      • Reconnect the connector to its original position.

    2. A0161HNE24

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 1 MΩ or more

    NG

    REPLACE CAN RH JUNCTION CONNECTOR

    OK

  7. RECONNECT CONNECTOR


    1. Reconnect the CAN main bus line connector (J81) to the CAN RH junction connector A side (w/ earth terminal).


    NEXT

  8. CHECK CAN LH JUNCTION CONNECTOR


    1. A0161BKE25

      Disconnect the CAN main bus line connector (J7) 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.

    2. A0161HNE24

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 1 MΩ or higher

    NG

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

    OK

    REPLACE CAN LH JUNCTION CONNECTOR

  9. RECONNECT CONNECTOR


    1. Reconnect the connector for the short-circuited branch line to the CAN junction connector (the connector that caused the bus line resistance to become normal (between 54 and 69 Ω) when it was disconnected).


    NEXT

  10. CHECK FOR SHORT IN CAN BUS WIRES


    1. A0161HNE24

      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

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 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).


    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH WIRE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

  11. RECONNECT CONNECTOR


    1. Reconnect the gateway ECU main bus line connector (J84) to the CAN RH junction connector B side (w/o earth terminal) .


    NEXT

  12. CHECK FOR SHORT IN CAN BUS WIRES (GATEWAY ECU)


    1. A0161HNE24

      Disconnect the gateway ECU connector (J76).

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 108 to 132 Ω

      Tech Tips

      If the resistance becomes normal (between 108 to 132 Ω) when the connector is disconnected, there may be a short in the gateway ECU.


    NG

    REPAIR OR REPLACE CAN BUS MAIN WIRE (GATEWAY ECU MAIN BUS LINE)

    OK

    REPLACE GATEWAY ECU Click here

  13. RECONNECT CONNECTOR


    1. Reconnect the ECM main bus line connector (J2) to the CAN LH junction connector A side (w/ earth terminal) .


    NEXT

  14. CHECK FOR SHORT IN CAN BUS WIRES (ECM)


    1. A0161HNE24

      Disconnect the ECM connector (A5).

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

      Standard Resistance
      Tester Connection Switch Condition Specified Value
      J21-6 (CANH) - J21-14 (CANL) Engine switch off 1 MΩ or higher

      Tech Tips


      • Measure the resistance with the gateway ECU main bus line connector (J84) disconnected.

      • If the resistance changes to 1 MΩ or more when the connector is disconnected, there may be a short in the ECM.


    NG

    REPAIR OR REPLACE CAN BUS MAIN WIRE (ECM MAIN BUS LINE)

    OK

    REPLACE ECM Click here