CAN COMMUNICATION SYSTEM(for LHD) Check CAN Bus Line for Short to GND

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 the DLC3.

  • Short in CAN main bus line

  • Short in CAN branch line

  • Combination meter assembly

  • Power steering ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Steering sensor

  • Airbag ECU assembly

  • ECM

  • Skid control ECU (brake actuator assembly)

  • Air conditioning amplifier assembly

  • Certification ECU (smart key ECU assembly)

  • Clearance warning ECU assembly

  • Network gateway ECU

    (w/ Network Gateway ECU)

  • Option connector (bus buffer ECU)

    (w/o Network Gateway ECU)

  • Parking brake ECU assembly

  • Navigation receiver assembly

    (for Navigation Receiver Type)

  • Radio and display receiver assembly

    (for Radio and Display Type)

  • No. 3 CAN junction connector

  • No. 4 CAN junction connector

WIRING DIAGRAM

A01UF67E01
A01UCJNE01
A01UDXIE01

CAUTION / NOTICE / HINT

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 or any 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.

  • After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) 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 engine switch on (IG), wait at least 61 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more for 10 minutes 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

  • Before replacing the main body ECU (multiplex network body ECU), ECM or certification ECU (smart key ECU assembly), refer to Service Bulletin.

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.

  • 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 GND IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the G98 No. 4 CAN junction connector.

      A01UDD1C41
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to No. 3 CAN Junction Connector
      *c to Combination Meter Assembly *d to Certification ECU (Smart Key ECU Assembly)
      *e to Air Conditioning Amplifier Assembly *f to Clearance Warning ECU Assembly
      *g

      to Network Gateway ECU

      (w/ Network Gateway ECU)

      		 *h

      to Option Connector (Bus Buffer ECU)

      (w/o Network Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      G98-1 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 3 CAN junction connector
      G98-11 (CANL) - G9-4 (CG)
      G98-2 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Combination meter assembly
      G98-12 (CANL) - G9-4 (CG)
      G98-3 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      G98-13 (CANL) - G9-4 (CG)
      G98-5 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      G98-15 (CANL) - G9-4 (CG)
      G98-6 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly
      G98-16 (CANL) - G9-4 (CG)
      G98-7 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Network gateway ECU*1
      G98-17 (CANL) - G9-4 (CG)
      G98-7 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Option connector (bus buffer ECU)*2
      G98-17 (CANL) - G9-4 (CG)
      *1: w/ Network Gateway ECU
      *2: w/o Network Gateway ECU
      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main bus line) B
      NG (ECU or sensor CAN bus line) C

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 3 Click here

    B

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR)


    1. Disconnect the G97 No. 3 CAN junction connector.

      A01UDD1C42
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to DLC3
      *c to Steering Sensor *d to ECM
      *e to Main Body ECU (Multiplex Network Body ECU) *f to Airbag ECU Assembly
      *g to Parking Brake ECU Assembly *h to Skid Control ECU (Brake Actuator Assembly)
      *i to No. 4 CAN Junction Connector *j

      to Navigation Receiver Assembly

      (for Navigation Receiver Type)
      *k

      to Radio and Display Receiver Assembly

      (for Radio and Display Type)

      		 *l to Power Steering ECU Assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      G97-1 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher DLC3
      G97-11 (CANL) - G9-4 (CG)
      G97-2 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      G97-12 (CANL) - G9-4 (CG)
      G97-3 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher ECM
      G97-13 (CANL) - G9-4 (CG)
      G97-4 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      G97-14 (CANL) - G9-4 (CG)
      G97-5 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag ECU assembly
      G97-15 (CANL) - G9-4 (CG)
      G97-6 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Parking brake ECU assembly
      G97-16 (CANL) - G9-4 (CG)
      G97-7 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      G97-17 (CANL) - G9-4 (CG)
      G97-8 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 4 CAN junction connector
      G97-18 (CANL) - G9-4 (CG)
      G97-9 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Navigation receiver assembly*1
      G97-19 (CANL) - G9-4 (CG)
      G97-9 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio and display receiver assembly*2
      G97-19 (CANL) - G9-4 (CG)
      G97-10 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      G97-20 (CANL) - G9-4 (CG)
      *1: for Navigation Receiver Type
      *2: for Radio and Display Type
      Result
      Result Proceed to
      OK A
      NG (No. 4 CAN junction connector main bus line) B
      NG (DLC3 branch line) C
      NG (ECU or sensor CAN bus line) D

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

    C

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    D

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


    1. Reconnect all wire harness connectors.

    2. Disconnect the ECU or sensor connected to the CAN bus line that is shorted to ground.

      Tech Tips

      If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus lines. To determine the ECU or sensor that is connected to the shorted bus line, refer to Terminals of ECU.

      Click here

    3. A01UF8JC01
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G9-6 (CANH) - G9-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      G9-14 (CANL) - G9-4 (CG)

      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.

      Result
      Result
      OK
      NG

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR CAN BUS LINE OR CONNECTOR