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

DESCRIPTION

There may be a short circuit between one of the CAN bus wires 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 wire

  • Short to ground in CAN main bus branch wire

  • Power management control ECU

  • ECM

  • Plugin charge control ECU assembly

  • Main body ECU

  • Combination meter assembly

  • Brake booster with master cylinder (Skid control ECU)

  • Steering angle sensor

  • Power steering ECU assembly

  • Yaw rate and acceleration sensor

  • Certification ECU (Smart key ECU assembly)

  • Navigation ECU sub-assembly (Navigation receiver assembly)*1

  • Radio and display receiver assembly*2

  • CAN No. 1 junction connector

  • CAN No. 2 junction connector

WIRING DIAGRAM

A0043CPE02
A0041AFE02

INSPECTION PROCEDURE

Note


  • Turn the power switch off before measuring the resistances between CAN main bus wires and between CAN main bus branch wires.

  • Turn the power switch off before inspecting CAN bus wires for a ground short.

  • After the power 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 power 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 power 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.

PROCEDURE


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


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

    2. A00407VE03
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 1 Junction Connector)
      *b to DLC3

      Disconnect the DLC3 branch wire connector (L91) 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. A0041YHE89
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L55-6 (CANH) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      L55-14 (CANL) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN MAIN BUS BRANCH WIRE CONNECTED TO DLC3

    OK

  2. CHECK FOR SHORT TO GND IN CAN BUS WIRE


    1. Reconnect the DLC3 branch wire connector (L91) to the CAN No. 1 junction connector.

    2. A0041YHE89
      Text in Illustration
      *1 DLC3

      Disconnect the connectors 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 wires and CAN main bus wires 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.

      A0040SQE01
      Text in Illustration
      *A for Navigation Receiver Type *B for Radio and Display Type
      *1 Main Body ECU *2 Steering Angle Sensor
      *3 Combination Meter Assembly *4 Power Steering ECU Assembly
      *5 Brake Booster with Master Cylinder (Skid Control ECU) *6 DLC3
      *7 ECM *8 Navigation ECU Sub-assembly (Navigation Receiver Assembly)
      *9 Radio and Display Receiver Assembly *10 Certification ECU (Smart Key ECU Assembly)
      *11 Yaw Rate and Acceleration Sensor *12 Plugin Charge Control ECU Assembly
      *13 Power Management Control ECU *14 CAN No. 1 Junction Connector
      *15 CAN No. 2 Junction Connector - -
      A0041HWE19
      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)
      ECM L90 P V
      DLC3 L91 W Y
      Brake booster with master cylinder (Skid control ECU) L92 LG L
      Power steering ECU assembly L93 R W
      Combination meter assembly L94 P W
      Steering angle sensor L95 L W
      Main body ECU L96 BR W
      CAN main bus wire (bus wire connecting CAN No. 1 junction connector and CAN No. 2 junction connector) L97 V W
      A0040KQE02
      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)

      • Navigation ECU sub-assembly (Navigation receiver assembly)*1

      • Radio and display receiver assembly*2

      		 L98 G W
      Certification ECU (Smart key ECU assembly) L99 BE P
      Yaw rate and acceleration sensor L100 Y L
      Plugin charge control ECU assembly L101 B W
      Power management control ECU L102 B W
      CAN main bus wire (bus wire connecting CAN No. 1 junction connector and CAN No. 2 junction connector) L103 V W

      • *1: for Navigation receiver type

      • *2: for Radio and display type

      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 wires.

      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 wires 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 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 wires.) B

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


      1. Reconnect all of the connectors to the CAN junction connectors, except for the one that was disconnected last (the bus wire 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 one branch wire only.

        Tech Tips


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

        • 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 wiring harnesses, and to make future maintenance easier.

    5. When there is no short to GND in any of the bus wires 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 wires between the CAN No. 1 junction connector and CAN No. 2 junction connector.


    B

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

    A

  3. CHECK FOR SHORT TO GND IN CAN BUS WIRE (CAN NO. 1 J/C)


    1. A00442SE02
      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 wire connector (L97) 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.

    2. A0041YHE89
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L55-6 (CANH) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      L55-14 (CANL) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    NG

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

    OK

  4. CHECK FOR SHORT TO GND IN CAN BUS WIRE (CAN NO. 1 J/C - CAN NO. 2 J/C)


    1. Reconnect the CAN main bus wire connector (L97) to the CAN No. 1 junction connector.

    2. A004192E02
      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 wire connector (L103) 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. A0041YHE89
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L55-6 (CANH) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      L55-14 (CANL) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN MAIN BUS WIRE (CAN NO. 1 J/C - CAN NO. 2 J/C)

    OK

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

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


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

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

    3. A0041YHE89
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L55-6 (CANH) - L55-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      L55-14 (CANL) - L55-4 (CG) Cable disconnected from negative (-) auxiliary 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 WIRE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR