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

DESCRIPTION

There may be a short circuit between the CAN bus main wire and +B when no resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of the DLC3.

Symptom Trouble Area
No resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of DLC3.

  • Short to +B in CAN bus main wire

  • Short to +B in CAN bus branch wire

  • Power management control ECU

  • ECM

  • Main body ECU

  • Combination meter

  • Skid control ECU (Brake booster with master cylinder)

  • Steering angle sensor

  • Yaw rate sensor

  • Power steering ECU

  • Center airbag sensor assembly

  • Transmission control ECU

  • Certification ECU

  • Navigation ECU (Navigation receiver assembly)

  • CAN No. 1 junction connector

  • CAN No. 2 junction connector

WIRING DIAGRAM

A01JCLPE02
A01JB0CE04

INSPECTION PROCEDURE

Note


  • Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN 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 +B IN CAN BUS WIRE (CAN NO. 2 J/C)


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

    2. A01JAQEE36
      Text in Illustration
      *1

      Front view of wire harness connector

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

      Disconnect the CAN No. 2 junction connector.

    3. A01JBRRE04
      Text in Illustration
      *3 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L61-6 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L61-14 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

    NG

    CHECK FOR SHORT TO +B IN CAN BUS WIRE (CAN NO. 1 J/C) Click here

    OK

  2. CHECK FOR SHORT TO +B IN CAN BUS WIRE (CAN NO. 2 J/C)

    A01JDACE04

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      L95-5 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Center airbag sensor assembly
      L95-16 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L95-7 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Transmission control ECU
      L95-18 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L95-8 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Power management control ECU
      L95-19 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L95-9 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher ECM
      L95-20 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      Text in Illustration
      *1

      Front view of wire harness connector

      (to CAN No. 2 Junction Connector)

      		 *2 DLC3
      *3 to Center Airbag Sensor Assembly *4 to Transmission Control ECU
      *5 to Power Management Control ECU *6 to ECM
      Result
      Result Proceed to
      OK A
      NG (to ECU or sensor wire) B

    B

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

    A

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

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


    1. Disconnect the CAN No. 1 junction connector.

      A01JDACE03
      Text in Illustration
      *1

      Front view of wire harness connector

      (to CAN No. 1 Junction Connector)

      		 *2 DLC3
      *3 to Combination Meter *4 to Steering Angle Sensor
      *5 to Main Body ECU *6 to Power Steering ECU
      *7 to DLC3 *8 to Navigation ECU
      *9 to CAN No. 2 Junction Connector *10 to Yaw Rate Sensor
      *11 to Certification ECU *12 to Skid Control ECU

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      L94-1 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Combination meter
      L94-12 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-2 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Steering angle sensor
      L94-13 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-3 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Main body ECU
      L94-14 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-4 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Power steering ECU
      L94-15 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-5 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher DLC3
      L94-16 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-6 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Navigation ECU
      L94-17 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-7 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher CAN No. 2 junction connector
      L94-18 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-8 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Yaw rate sensor
      L94-19 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-9 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Certification ECU
      L94-20 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L94-10 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Skid control ECU
      L94-21 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      Result
      Result Proceed to
      OK A
      NG (to DLC3 branch wire) B
      NG (to CAN No. 2 J/C main wire) C
      NG (to ECU or sensor wire) D

    B

    REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO DLC3

    C

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

    D

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

    A

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

  4. CHECK FOR SHORT TO +B IN CAN BUS WIRE (ECU, SENSOR)


    1. Reconnect the CAN No. 1 Junction connector and CAN No. 2 junction connector.

    2. Disconnect the ECU or sensor connected to the CAN bus wire that is shorted to B+.

      Tech Tips

      If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus wires. To determine the ECU or sensor that is connected to the shorted bus wire, refer to the terminals of ECU tables Click here.

    3. A01JBRRE03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L61-6 (CANH) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      L61-14 (CANL) - L61-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Tech Tips

      If the resistance changes to 6 kΩ 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 WIRE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR