CAN COMMUNICATION SYSTEM Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus lines

  • Short in CAN branch lines

  • Central gateway ECU (network gateway ECU)

  • ECM

  • Combination meter assembly

  • Air conditioning amplifier assembly

  • Engine stop and start ECU (w/ Stop and Start System)

  • Power steering ECU assembly

  • Certification ECU (smart key ECU assembly)

  • Airbag sensor assembly

  • Yaw rate sensor

  • Main body ECU (multiplex network body ECU)

  • Skid control ECU (brake actuator assembly)

  • Steering sensor

  • Front steering control ECU (w/ VGRS System)

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

WIRING DIAGRAM

Figure 1. for LHD:

B003SW3E01
B003X7VE01

Figure 2. for RHD:

B003TRAE01
B003WH1E01

CAUTION / NOTICE / HINT

Note


  • 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

  • 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

  • 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) and wait at least 60 seconds, turn the lane departure alert system on using the LDA main switch, turn the dynamic radar cruise control system on using the cruise control main switch, and then drive the vehicle at a speed of 40 km/h (25 mph) or more for 5 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 as normal.

    Click here

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

Tech Tips


  • Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.

  • When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE


  1. CHECK VEHICLE TYPE


    1. Check vehicle type.

      Result
      Result Proceed to
      for LHD A
      for RHD B

    B

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

    A

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


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

    2. B003T6OC01
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the K3 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K3-29 (CANH) - K3-30 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK A
      NG (for 2GR-FSE Engine) B
      NG (for 8AR-FTS Engine) C

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

    C

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

    B

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


    1. Reconnect the K3 combination meter assembly connector.

    2. B003V7YC62
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A77 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-14 (CANH) - A77-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    GO TO STEP 5 Click here

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


    1. Reconnect the K3 combination meter assembly connector.

    2. B003X86C51
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A91 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A91-13 (CANH) - A91-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  5. CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the A77*1 or A91*2 ECM connector.


      • *1: for 2GR-FSE Engine

      • *2: for 8AR-FTS Engine

    2. Disconnect the K109 No. 1 CAN junction connector.

      B003X5NC30
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b to No. 2 CAN Junction Connector
      *c to Combination Meter Assembly *d

      to Engine Stop and Start ECU

      (w/ Stop and Start System)
      *e to Central Gateway ECU (Network Gateway ECU) *f to Air Conditioning Amplifier Assembly
      *g to Certification ECU (Smart Key ECU Assembly) *h to Power Steering ECU Assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K109-1 (CANH) - K109-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction connector
      K109-2 (CANH) - K109-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      K109-3 (CANH) - K109-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Engine stop and start ECU*
      K109-4 (CANH) - K109-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      K109-5 (CANH) - K109-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      K109-7 (CANH) - K109-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      K109-9 (CANH) - K109-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly

      • *: w/ Stop and Start System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 2 CAN junction connector) B
      NG (Line to combination meter assembly) C
      NG (Line to central gateway ECU (network gateway ECU)) D
      NG (Line to ECU or sensor) E

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)

    D

    CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

    E

    GO TO STEP 14 Click here

    B

  6. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the K109 No. 1 CAN junction connector.

    2. Disconnect the K110 No. 2 CAN junction connector.

      B003X5NC31
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to No. 1 CAN Junction Connector
      *c to Main Body ECU (Multiplex Network Body ECU) *d to ECM
      *e to Airbag Sensor Assembly *f to Yaw Rate Sensor
      *g to Steering Sensor *h to Skid Control ECU (Brake Actuator Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K110-1 (CANH) - K110-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 1 CAN junction connector
      K110-2 (CANH) - K110-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      K110-3 (CANH) - K110-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      K110-5 (CANH) - K110-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      K110-6 (CANH) - K110-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Yaw rate sensor
      K110-9 (CANH) - K110-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      K110-10 (CANH) - K110-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      Result
      Result Proceed to
      OK A
      NG (Line to No. 1 CAN junction connector) B
      NG (Line to ECM) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    B

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

    C

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

    D

    GO TO STEP 14 Click here

  7. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Reconnect the K109 No. 1 CAN junction connector.

    2. B003VK4C22
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

      Disconnect the K141 central gateway ECU (network gateway ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K141-18 (CA4H) - K141-17 (CA4L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


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

    2. B003T6OC01
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the K3 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K3-29 (CANH) - K3-30 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK A
      NG (for 2GR-FSE Engine) B
      NG (for 8AR-FTS Engine) C

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

    C

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

    B

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


    1. Reconnect the K3 combination meter assembly connector.

    2. B003V7YC62
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A77 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A77-14 (CANH) - A77-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    GO TO STEP 11 Click here

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


    1. Reconnect the K3 combination meter assembly connector.

    2. B003X86C51
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A91 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A91-13 (CANH) - A91-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  11. CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the A77*1 or A91*2 ECM connector.


      • *1: for 2GR-FSE Engine

      • *2: for 8AR-FTS Engine

    2. Disconnect the K109 No. 1 CAN junction connector.

      B003X5NC32
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b to No. 2 CAN Junction Connector
      *c to Combination Meter Assembly *d

      to Engine Stop and Start ECU

      (w/ Stop and Start System)
      *e to Airbag Sensor Assembly *f to Yaw Rate Sensor
      *g to Skid Control ECU (Brake Actuator Assembly) *h to Steering Sensor

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K109-1 (CANH) - K109-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction connector
      K109-2 (CANH) - K109-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      K109-3 (CANH) - K109-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Engine stop and start ECU*
      K109-4 (CANH) - K109-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      K109-5 (CANH) - K109-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Yaw rate sensor
      K109-6 (CANH) - K109-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      K109-7 (CANH) - K109-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor

      • *: w/ Stop and Start System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 2 CAN junction connector) B
      NG (Line to combination meter assembly) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 1 CAN JUNCTION CONNECTOR)

    D

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

    B

  12. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR)


    1. Reconnect the K109 No. 1 CAN junction connector.

    2. Disconnect the K110 No. 2 CAN junction connector.

      B003X5NC33
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to No. 1 CAN Junction Connector
      *c to Main Body ECU (Multiplex Network Body ECU) *d to ECM
      *e to Central Gateway ECU (Network Gateway ECU) *f to Air Conditioning Amplifier Assembly
      *g

      to Front Steering Control ECU

      (w/ VGRS System)

      		 *h to Certification ECU (Smart Key ECU Assembly)
      *i to Power Steering ECU Assembly - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K110-1 (CANH) - K110-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 1 CAN junction connector
      K110-2 (CANH) - K110-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      K110-3 (CANH) - K110-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      K110-5 (CANH) - K110-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      K110-6 (CANH) - K110-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      K110-7 (CANH) - K110-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Front steering control ECU*
      K110-8 (CANH) - K110-18 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      K110-10 (CANH) - K110-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly

      • *: w/ VGRS System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 1 CAN junction connector) B
      NG (Line to ECM) C
      NG (Line to central gateway ECU (network gateway ECU)) D
      NG (Line to ECU or sensor) E

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    B

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

    C

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

    E

    GO TO STEP 14 Click here

    D

  13. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Reconnect the K110 No. 2 CAN junction connector.

    2. B003VK4C22
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

      Disconnect the K141 central gateway ECU (network gateway ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K141-18 (CA4H) - K141-17 (CA4L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


    1. Reconnect all wire harness connectors.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

      Click here

    3. B003U8MC08
      *a

      Component with harness connected

      (Central Gateway ECU (Network Gateway ECU))

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K141-18 (CA4H) - K141-17 (CA4L) 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.

      Result
      Result
      OK
      NG

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR