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

DESCRIPTION

There may be a short circuit between the V1 bus main wires and/or CAN branch wires when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

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

  • Short in CAN main bus wire

  • Short 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 IN CAN BUS WIRES (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. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

    NG

    REPAIR OR REPLACE CAN MAIN BUS BRANCH WIRE CONNECTED TO DLC3

    OK

  2. CHECK FOR SHORT IN CAN BUS WIRES (BRANCH WIRE)


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

    2. A0041YHE85
      Text in Illustration
      *1 DLC3

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

    3. While observing the resistance value shown on the tester, disconnect connectors (L92, L93, L94, L95, L96, L98, L99, L100 and L102) from the CAN No. 1 junction connector or CAN No. 2 junction connector one by one until the resistance becomes normal (between 54 and 69 Ω).

      Tech Tips

      Disconnect each branch wire connector other than that of the DLC3.

      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 in 2 or more branch wires.

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

    4. When there is a short in one or more of the branch wires:


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


    B

    CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR) Click here

    A

  3. CHECK FOR SHORT IN CAN BUS WIRES (PLUGIN CHARGE CONTROL ECU ASSEMBLY MAIN BUS WIRE)


    1. A0040G5E02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 2 Junction Connector)
      *b to Plugin Charge Control ECU Assembly

      Disconnect the plugin charge control ECU assembly main bus wire connector (L101) 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. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Symptom Proceed to
      The resistance is still below 54 Ω when the plugin charge control ECU assembly connector is disconnected. (There are no shorts in the plugin charge control ECU assembly or between its main bus wires.) A
      The resistance falls within the specified range (between 108 and 132 Ω) (the other terminating resistor is normal) when the plugin charge control ECU assembly connector is disconnected. (There is a short in the plugin charge control ECU assembly or between its main bus wires.) B

    B

    CHECK FOR SHORT IN CAN BUS WIRES (PLUGIN CHARGE CONTROL ECU ASSEMBLY) Click here

    A

  4. CHECK FOR SHORT IN CAN BUS WIRES (ECM MAIN BUS WIRE)


    1. A0043WOE02
      Text in Illustration
      *a

      Rear view of wire harness connector

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

      Disconnect the ECM main bus wire connector (L90) 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. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the plugin charge control ECU assembly main bus wire connector (L101) 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 or between its main bus wires.) A
      The resistance becomes 1 MΩ or more when the ECM connector is disconnected. (There is a short in the ECM or between its main bus wires.) B

    B

    CHECK FOR SHORT IN CAN BUS WIRES (ECM) Click here

    A

  5. CHECK FOR SHORT IN CAN BUS WIRES (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. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

    NG

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

    OK

  6. CHECK FOR SHORT IN CAN BUS WIRES (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. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

    NG

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

    OK

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

  7. CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR)


    1. Reconnect the connector for the short-circuited branch wire to the CAN junction connector (the connector that caused the bus wire resistance to become normal (between 54 and 69 Ω) 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 short-circuited branch wire is connected Click here.

    3. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 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 WIRES OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

  8. CHECK FOR SHORT IN CAN BUS WIRES (PLUGIN CHARGE CONTROL ECU ASSEMBLY)


    1. Reconnect the plugin charge control ECU assembly main bus wire connector (L101) to the CAN No. 2 junction connector.

    2. Disconnect the S21 plugin charge control ECU assembly connector.

    3. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 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 plugin charge control ECU assembly.


    NG

    REPAIR OR REPLACE CAN MAIN BUS WIRES (PLUGIN CHARGE CONTROL ECU ASSEMBLY MAIN WIRES)

    OK

    REPLACE PLUGIN CHARGE CONTROL ECU ASSEMBLY Click here

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


    1. Reconnect the ECM main bus line connector (L90) to the CAN No. 1 junction connector.

    2. Disconnect the A56 ECM connector.

    3. A0041YHE85
      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) - L55-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

      Tech Tips


      • Measure the resistance with the plugin charge control ECU assembly main bus wire connector (L101) 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 MAIN BUS WIRES (ECM MAIN WIRES)

    OK

    REPLACE ECM Click here