CAN COMMUNICATION SYSTEM Check CAN Bus Lines for Short Circuit

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 in CAN main bus line

  • Short in CAN branch line

  • Power management control ECU

  • ECM

  • Main body ECU (Multiplex network body ECU)

  • Combination meter assembly

  • Brake booster with master cylinder assembly (Skid control ECU)

  • Steering sensor

  • Power steering ECU assembly

  • Airbag sensor assembly

  • Air conditioning amplifier assembly

  • Smart key ECU assembly (Certification ECU)

  • Navigation receiver assembly*1

  • Navigation ECU sub-assembly*2

  • Radio and display receiver assembly*3

  • CAN junction LH connector

  • CAN junction RH connector

  • Clearance warning ECU assembly*4

WIRING DIAGRAM

A01HT87E01
A01HSZIE02

INSPECTION PROCEDURE

Note


  • Before measuring the resistance of the CAN bus, turn the power 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 (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work Click here.

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

  • DTC check procedure: Turn the power switch on (IG), turn the cruise control main switch on, turn the blind spot monitor main switch on, wait at least 60 seconds and then drive the vehicle at a speed of 20 km/h (12 mph) or more for 11 seconds or more.

  • After the repair, perform the 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 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.

  • 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 (-) auxiliary battery terminal.

    2. A01HTTQE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction LH Connector)
      *b to DLC3

      Disconnect the DLC3 branch line connector (I96) from the CAN junction LH connector.

      Note


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

      • Reconnect the connector to its original position.

    3. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (CANL) Cable disconnected from negative (-) auxiliary 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 (BRANCH LINE)


    1. Reconnect the DLC3 branch line connector (I96) to the CAN junction LH connector.

    2. A01HSIFE47
      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 (I110, I95, I97, I109, I100, I107, I106, I102, I111 and I103) from the CAN junction LH connector or CAN junction RH 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.

      A01HU4UE01
      Text in Illustration
      *A w/ Intuitive Parking Assist System *B for Navigation Receiver Type
      *C for Radio and Display Type (w/ Intuitive Parking Assist System) *D for Radio and Display Type (w/o Intuitive Parking Assist System)
      *1 Clearance Warning ECU Assembly *2 ECM
      *3 Air Conditioning Amplifier Assembly *4 Airbag Sensor Assembly
      *5 Smart Key ECU Assembly (Certification ECU) *6 Power Steering ECU Assembly
      *7 Navigation Receiver Assembly *8 Navigation ECU Sub-assembly
      *9 Radio and Display Receiver Assembly *10 Combination Meter Assembly
      *11 Power Management Control ECU *12 DLC3
      *13 Brake Booster with Master Cylinder Assembly (Skid Control ECU) *14 Steering Sensor
      *15 Main Body ECU (Multiplex Network Body ECU) *16 CAN Junction RH Connector
      *17 CAN Junction LH Connector - -
      A01HVRXE01
      Text in Illustration
      *a

      Component without harness connected

      (CAN Junction LH Connector)

      		 - -
      Wiring Color
      CAN Junction LH Connector Side Code Color (CANH Side) Color (CANL Side)
      CAN main bus line (bus line connecting CAN junction LH connector and CAN junction RH connector) I93 B W
      Combination meter assembly I94 R W
      Brake booster with master cylinder assembly (Skid control ECU) I110 Y W
      DLC3 I96 L W
      Power management control ECU I109 G W
      Steering sensor I97 V W
      Main body ECU (Multiplex network body ECU) I95 P W
      A01HSU3E03
      Text in Illustration
      *a

      Component without harness connected

      (CAN Junction RH Connector)

      		 - -
      Wiring Color
      CAN Junction RH Connector Side Code Color (CANH Side) Color (CANL Side)
      Clearance warning ECU assembly*4 I111 BE W
      ECM I104 P W
      Air conditioning amplifier assembly I102 V W
      Airbag sensor assembly I103 Y W
      Smart key ECU assembly (Certification ECU) I106 L W
      Power steering ECU assembly I100 G W

      • Navigation receiver assembly*1

      • Navigation ECU sub-assembly*2

      • Radio and display receiver assembly*3

      		 I107 R W
      CAN main bus line (bus line connecting CAN junction LH connector and CAN junction RH connector) I101 B W

      • *1: for Navigation receiver type

      • *2: for Radio and display type (w/ Intuitive parking assist system)

      • *3: for Radio and display type (w/o Intuitive parking assist system)

      • *4: w/ Intuitive parking assist system

      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 between a pair of 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 (ECU, SENSOR) Click here

    A

  3. CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY MAIN BUS LINE)


    1. A01HU77E01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction LH Connector)
      *b to Combination Meter Assembly

      Disconnect the combination meter assembly main bus line connector (I94) from the CAN junction LH connector.

      Note


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

      • Reconnect the connector to its original position.

    2. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (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 combination meter assembly connector is disconnected. (There are no shorts in the combination meter assembly 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 combination meter assembly connector is disconnected. (There is a short in the combination meter assembly or between its main bus lines.) B

    B

    CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY) Click here

    A

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


    1. A01HSVQE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction RH Connector)
      *b to ECM

      Disconnect the ECM main bus line connector (I104) from the CAN junction RH connector.

      Note


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

      • Reconnect the connector to its original position.

    2. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

      Tech Tips

      Measure the resistance with the combination meter assembly main bus line connector (I94) 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 lines.) 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 lines.) B

    B

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

    A

  5. CHECK FOR SHORT IN CAN BUS LINES (CAN J/C LH)


    1. A01HT6UE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction LH Connector)
      *b to CAN Junction RH Connector

      Disconnect the CAN main bus line connector (I93) from the CAN junction LH connector.

      Note


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

      • Reconnect the connector to its original position.

    2. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

    NG

    REPLACE CAN JUNCTION LH CONNECTOR

    OK

  6. CHECK FOR SHORT IN CAN BUS LINES (CAN J/C LH - CAN J/C RH)


    1. Reconnect the CAN main bus line connector (I93) to the CAN junction LH connector.

    2. A01HUT0E01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction RH Connector)
      *b to CAN Junction LH Connector

      Disconnect the CAN main bus line connector (I101) from the CAN junction RH connector.

      Note


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

      • Reconnect the connector to its original position.

    3. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (CAN J/C LH - CAN J/C RH)

    OK

    REPLACE CAN JUNCTION RH CONNECTOR

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


    1. Reconnect the connector for the short-circuited branch line to the CAN J/C (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. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (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 LINES OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

  8. CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY)


    1. Reconnect the combination meter assembly main bus line connector (I94) to the CAN junction LH connector.

    2. Disconnect the combination meter assembly connector.

    3. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (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 combination meter assembly.


    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (COMBINATION METER ASSEMBLY MAIN LINES)

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

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


    1. Reconnect the ECM main bus line connector (I104) to the CAN junction RH connector.

    2. Disconnect the ECM connector.

    3. A01HSIFE47
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher

      Tech Tips


      • Measure the resistance with the combination meter assembly main bus line connector (I94) 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 LINES (ECM MAIN LINES)

    OK

    REPLACE ECM Click here