CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU) Check CAN Bus Line for Short to GND (RHD Models)

DESCRIPTION

There may be a short circuit between one of the CAN bus lines 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 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 with motor assembly

  • Airbag sensor assembly

  • Air conditioning amplifier assembly

  • Certification ECU (smart key ECU assembly)

  • Multi-media module receiver assembly*1

  • Radio receiver assembly*2

  • Clearance warning ECU assembly

  • CAN junction connector LH1

  • CAN junction connector RH1

WIRING DIAGRAM

A00084BE02
A0004W4E03

CAUTION / NOTICE / HINT

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 or any 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 36 km/h (22 mph) or more for 7 seconds 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.

  • If the main body ECU (multiplex network body ECU) is replaced, refer to Service Bulletin.

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 the 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 wire harnesses, and to make future maintenance easier.

PROCEDURE


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


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

    2. A000587E02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction Connector RH1)
      *b to DLC3

      Disconnect the H119 DLC3 branch line connector.

      Note


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

      • Reconnect the connector to its original position.

    3. A000965E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    OK

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE


    1. Reconnect the H119 DLC3 branch line connector.

    2. A000965E03
      Text in Illustration
      *1 DLC3

      Disconnect the connectors from the CAN junction connector LH1 and CAN junction connector RH1 one at a time.

      Tech Tips

      Disconnect the ECU and sensor connectors other than the DLC3 branch lines and CAN main bus lines between the CAN junction connector LH1 and CAN junction connector RH1.

    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.

      A0006T6E02
      Text in Illustration
      *A for Navigation Receiver Type *B for Radio and Display Type
      *1 Multi-media Module Receiver Assembly *2 Radio Receiver Assembly
      *3 Power Steering ECU with Motor Assembly *4 Main Body ECU (Multiplex Network Body ECU)
      *5 Airbag Sensor Assembly *6 ECM
      *7 Air Conditioning Amplifier Assembly *8 Power Management Control ECU
      *9 Brake Booster with Master Cylinder Assembly (Skid Control ECU) *10 Combination Meter Assembly
      *11 DLC3 *12 Certification ECU (Smart Key ECU Assembly)
      *13 Clearance Warning ECU Assembly *14 Steering Sensor
      *15 CAN Junction Connector LH1 *16 CAN Junction Connector RH1
      A0008Z6E05
      Text in Illustration
      *a

      Component without harness connected

      (CAN Junction Connector RH1)

      		 - -
      Wiring Color
      CAN Junction Connector RH1 Side Code Color (CANH Side) Color (CANL Side)
      Brake booster with master cylinder assembly (skid control ECU) H131 B W
      CAN main bus line (bus line connecting CAN junction connector LH1 and CAN junction connector RH1) H122 R W
      Combination meter assembly H117 G W
      DLC3 H119 L W
      Certification ECU (smart key ECU assembly) H127 V W
      Clearance warning ECU assembly H132 P W
      Steering sensor H120 BE W
      A00085KE15
      Text in Illustration
      *a

      Component without harness connected

      (CAN Junction Connector LH1)

      		 - -
      Wiring Color
      CAN Junction Connector LH1 Side Code Color (CANH Side) Color (CANL Side)

      • Multi-media module receiver assembly*1

      • Radio receiver assembly*2

      		 H128 BE W
      Power steering ECU with motor assembly H121 P W
      Main body ECU (multiplex network body ECU assembly) H118 V W
      Airbag sensor assembly H124 Y W
      ECM H125 L W
      Air conditioning amplifier assembly H123 G W
      CAN main bus line (bus line connecting CAN junction connector LH1 and CAN junction connector RH1) H116 R W
      Power management control ECU H130 B 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 lines.

      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 lines between the CAN junction connector LH1 and CAN junction connector RH1.) A
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) becomes normal (200 Ω or higher) 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 lines.) B

    4. When there is a short to GND in one or more of the bus lines 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 line that is shorted to GND). Check that the resistance shown on the tester is normal (200 Ω or higher) to confirm that there is a short to GND 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 wire harnesses, and to make future maintenance easier.

    5. When there is no short to GND in any of the bus lines 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 main bus lines between the CAN junction connector LH1 and CAN junction connector RH1.


    B

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

    A

  3. CHECK FOR SHORT TO GND IN CAN BUS LINE (CAN J/C RH1)


    1. A00068SE02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction Connector RH1)
      *b to CAN Junction Connector LH1

      Disconnect the H122 CAN main bus line connector.

      Note


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

      • Reconnect the connector to its original position.

    2. A000965E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    NG

    REPLACE CAN JUNCTION CONNECTOR RH1

    OK

  4. CHECK FOR SHORT TO GND IN CAN BUS LINE (CAN J/C LH1 - CAN J/C RH1)


    1. Reconnect the H122 CAN main bus line connector.

    2. A0004WJE02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction Connector LH1)
      *b to CAN Junction Connector RH1

      Disconnect the H116 CAN main bus line connector.

      Note


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

      • Reconnect the connector to its original position.

    3. A000965E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    OK

    REPLACE CAN JUNCTION CONNECTOR LH1

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINE (CAN J/C LH1 - CAN J/C RH1)

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


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

    2. A000965E03
      Text in Illustration
      *1 DLC3

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (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).


    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR