CAN COMMUNICATION SYSTEM (for LHD) Short in CAN Bus Lines

DESCRIPTION

There may be a short circuit between the V Bus main lines and/or CAN branch lines 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 between CAN bus lines

  • ECM

  • Parking brake ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Spiral with sensor cable sub-assembly (steering angle sensor)

  • Yaw rate sensor

  • Headlight swivel ECU assembly (AFS ECU)

  • Combination meter assembly

  • Brake actuator assembly (skid control ECU)

  • Power steering ECU assembly

  • Air conditioning amplifier assembly

  • Network gateway ECU*1

  • Front steering control ECU*2

  • Center airbag sensor assembly

  • Multi-media module receiver assembly

  • Certification ECU (smart key ECU assembly)

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

  • No. 3 CAN junction connector

WIRING DIAGRAM

A01FEXHE01
A01FFB9E01
A01FFKIE03

INSPECTION PROCEDURE

Note


  • Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output Click here.

  • After turning the engine switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.

  • Before replacing the certification ECU (smart key ECU assembly), refer to the entry and start system (for Entry Function) Click here.

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • DTC check procedure: Allow the radar cruise control system (vehicle control mode) to operate for 1 second or more.

  • After the repair, perform CAN Bus Check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.

Tech Tips


  • Operating the engine 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.

  • 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.

  • Connectors that connect to the CAN junction connector can be distinguished by color of their CAN bus lines. When the connectors have been disconnected from the CAN junction connector, 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.

PROCEDURE


  1. CHECK FOR SHORT IN CAN BUS LINES (DLC3 BRANCH LINE)


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

      A01FG42E19
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N109 G W DLC3

    2. Disconnect the DLC3 branch line connector from the No. 2 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

    NG

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    OK

  2. CHECK FOR SHORT IN CAN BUS LINES


    1. Reconnect the DLC3 branch line connector to the No. 2 CAN junction connector.

    2. A01FDXFE01
      Text in Illustration
      *a Front view of 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 N107, N108, N109, N110, N111, N112, N113, N114, N115, N116, N117, N118, N119, N120, N121, N122, U48, U49, U50 and U51 from the No. 1 CAN junction connector, No. 2 CAN junction connector or No. 3 CAN 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.

      A01FII5E01
      Text in Illustration
      *1 No. 1 CAN Junction Connector *2 No. 2 CAN Junction Connector
      *3 No. 3 CAN Junction Connector *4 ECM
      *5 Parking Brake ECU Assembly *6 Main Body ECU (Multiplex Network Body ECU)
      *7 DLC3 *8 Yaw Rate Sensor
      *9 Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor) *10 Brake Actuator Assembly (Skid Control ECU)
      *11 Headlight Swivel ECU Assembly (AFS ECU) *12 Combination Meter Assembly
      *13 Power Steering ECU Assembly *14 Network Gateway ECU (w/ Network Gateway ECU)
      *15 Multi-media Module Receiver Assembly *16 Air Conditioning Amplifier Assembly
      *17 Center Airbag Sensor Assembly *18 Front Steering Control ECU (w/ Variable Gear Ratio Steering System)
      *19 Certification ECU (Smart Key ECU Assembly) - -
      A01FF4ZE04
      Text in Illustration
      *1 No. 1 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 - -
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      U48 B W Parking Brake ECU Assembly
      U49 R W Main Body ECU (Multiplex Network Body ECU)
      U50 P W No. 2 CAN Junction Connector
      U51 G W ECM
      A01FIRAE08
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 - -
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N107 B W No. 3 CAN Junction Connector
      N108 R W Spiral with Sensor Cable Sub-assembly (Steering Angle Sensor)
      N109 G W DLC3
      N110 B W Yaw Rate Sensor
      N111 Y W Headlight Swivel ECU Assembly (AFS ECU)
      N112 V W Combination Meter Assembly
      N113 P W No. 1 CAN Junction Connector
      N114 L W Brake Actuator Assembly (Skid Control ECU)
      A01FIRAE09
      Text in Illustration
      *1 No. 3 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 - -
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N115 L W Power Steering ECU Assembly
      N116 G W Network Gateway ECU*1
      N117 R W Air Conditioning Amplifier Assembly
      N118 Y W Certification ECU (Smart Key ECU Assembly)
      N119 V W Front Steering Control ECU*2
      N120 P W Center Airbag Sensor Assembly
      N121 B W No. 2 CAN Junction Connector
      N122 B W Multi-media Module Receiver Assembly

      • *1: w/ Network Gateway ECU

      • *2: w/ Variable Gear Ratio Steering System

      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
      Result Proceed to
      The resistance is still below 54 Ω when all the specified connectors are disconnected. (There are no shorts between a pair of the branch lines.) 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 lines.) B

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


      1. Reconnect all of the connectors to the CAN J/C, 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 one branch line only.

        Tech Tips


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

        • 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 LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR) Click here

    A

  3. CHECK FOR SHORT IN CAN BUS LINES (ECM MAIN BUS LINE)


    1. Disconnect the ECM main bus line connector from the No. 1 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

      A01FH24E05
      Text in Illustration
      *1 No. 1 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      U51 G W ECM

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      The resistance is still below 54 Ω when the ECM connector is disconnected. (There are no shorts in the ECM or between its main bus lines.) A
      The resistance falls within the specified range (between 108 and 132 Ω) (the other terminating resistor is normal) when the ECM connector is disconnected. (There is a short in the ECM or between its main bus lines.) B

    B

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

    A

  4. CHECK FOR SHORT IN CAN BUS LINES (CERTIFICATION ECU MAIN BUS LINE)


    1. Disconnect the certification ECU (smart key ECU assembly) main bus line connector from the No. 3 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

      A01FG42E24
      Text in Illustration
      *1 No. 3 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N118 Y W Certification ECU (Smart Key ECU Assembly)

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the ECM main bus line connector disconnected.

      Result
      Result Proceed to
      The resistance is still below 1 MΩ when the certification ECU (smart key ECU assembly) connector is disconnected. (There are no shorts in the certification ECU [smart key ECU assembly] or between its main bus lines.) A
      The resistance becomes 1 MΩ or more when the certification ECU (smart key ECU assembly) connector is disconnected. (There is a short in the certification ECU [smart key ECU assembly] or between its main bus lines.) B

    B

    CHECK FOR SHORT IN CAN BUS LINES (CERTIFICATION ECU) Click here

    A

  5. CHECK NO. 1 CAN JUNCTION CONNECTOR


    1. Disconnect the CAN main bus line connector from the No. 1 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

      A01FH24E07
      Text in Illustration
      *1 No. 1 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      U50 P W No. 2 CAN Junction Connector

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the certification ECU (smart key ECU assembly) main bus line connector disconnected.


    NG

    CHECK NO. 3 CAN JUNCTION CONNECTOR Click here

    OK

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

  6. CHECK NO. 3 CAN JUNCTION CONNECTOR


    1. Reconnect the CAN main bus line connector from the No. 1 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

      A01FG42E27
      Text in Illustration
      *1 No. 3 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N121 B W No. 2 CAN Junction Connector

    2. Disconnect the CAN main bus line connector from the No. 3 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the ECM main bus line connector disconnected.


    NG

    CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR) Click here

    OK

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

  7. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the CAN main bus line connector from the No. 3 CAN junction connector.

      A01FG42E25
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N113 P W No. 1 CAN Junction Connector

    2. Disconnect the CAN main bus line connector from the No. 2 CAN junction connector.

      Note


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

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the certification ECU (smart key ECU assembly) main bus line connector disconnected.


    NG

    CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR) Click here

    OK

    REPAIR OR REPLACE CAN BUS MAIN LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)

  8. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)


    1. Disconnect the CAN main bus line connector from the No. 2 CAN junction connector.

      A01FG42E26
      Text in Illustration
      *1 No. 2 CAN Junction Connector - -
      *a

      Rear view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b Front view of DLC3
      Wiring Color
      Code Color (CANH Side) Color (CANL Side) Connect to
      N107 B W No. 3 CAN Junction Connector

      Note


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

      • Reconnect the connector to its original position.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the ECM main bus line connector disconnected.


    NG

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    OK

    REPAIR OR REPLACE CAN BUS MAIN LINES (NO. 2 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

  9. CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)


    1. A01FDXFE01
      Text in Illustration
      *a Front view of DLC3

      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).

    2. Disconnect the connector that includes the DLC3 connected CAN lines (such as CANH and CANL) from the ECU (or sensor) to which the short-circuited branch line is connected Click here.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) 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 BUS LINE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

  10. CHECK FOR SHORT IN CAN BUS LINES (ECM)


    1. A01FDXFE01
      Text in Illustration
      *a Front view of DLC3

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

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK (for 2GR-FSE) A
      OK (for 4GR-FSE) B
      NG C

      Tech Tips

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


    B

    REPLACE ECM Click here

    C

    REPAIR OR REPLACE CAN BUS MAIN LINES (ECM MAIN BUS LINES)

    A

    REPLACE ECM Click here

  11. CHECK FOR SHORT IN CAN BUS LINES (CERTIFICATION ECU)


    1. A01FDXFE01
      Text in Illustration
      *a Front view of DLC3

      Reconnect the certification ECU (smart key ECU assembly) main bus line connector to the No. 3 CAN junction connector.

    2. Disconnect the certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Connection Specified Condition
      N20-6 (CANH) - N20-14 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher

      Tech Tips


      • Measure the resistance with the ECM main bus line connector 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 LINES (CERTIFICATION ECU MAIN BUS LINES)

    OK

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)