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 the 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

  • Power steering ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Steering sensor

  • Airbag sensor assembly

  • Skid control ECU assembly

  • Air conditioning amplifier assembly

  • Certification ECU (smart key ECU assembly)

  • Stereo component equalizer assembly

    (w/ ASC System)

  • Yaw rate sensor

  • Hybrid vehicle control ECU assembly

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

WIRING DIAGRAM

Figure 1. for LHD

B003YGBE01
B003Y6VE01

Figure 2. for RHD

B003XU5E01
B003Y4GE01

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) and wait at least 60 seconds. Turn the lane departure alert main switch on and then drive the vehicle at a speed of 36 km/h (22 mph) or more for 300 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 as normal.

    Click here

  • If the main body ECU (multiplex network body ECU) is replaced, 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 (-) auxiliary battery terminal.

    2. Disconnect the K3 combination meter assembly connector.

    3. B003YEAC21
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      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 (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

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


    1. Reconnect the K3 combination meter assembly connector.

    2. Disconnect the A78 ECM connector.

    3. B003XRUC15
      *a

      Front view of wire harness connector

      (to ECM)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A78-13 (CANH) - A78-26 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

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


    1. Reconnect the A78 ECM connector.

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

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

      B003YKYC26
      *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 Central Gateway ECU (Network Gateway ECU)
      *e to Air Conditioning Amplifier Assembly *f

      to Stereo Component Equalizer Assembly

      (w/ ASC System)
      *g to Certification ECU (Smart Key ECU Assembly) *h to Hybrid Vehicle Control ECU Assembly
      *i to Power Steering ECU Assembly - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K109-1 (CANH) - K109-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 2 CAN junction connector
      K109-2 (CANH) - K109-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Combination meter assembly
      K109-4 (CANH) - K109-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      K109-5 (CANH) - K109-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Air conditioning amplifier assembly
      K109-6 (CANH) - K109-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Stereo component equalizer assembly*
      K109-7 (CANH) - K109-17 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      K109-8 (CANH) - K109-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Hybrid vehicle control ECU assembly
      K109-9 (CANH) - K109-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Power steering ECU assembly

      • *: w/ ASC System

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

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 11 Click here

    D

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

    E

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

    B

  5. 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.

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

      B003YKYC27
      *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 Assembly
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K110-1 (CANH) - K110-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 1 CAN junction connector
      K110-2 (CANH) - K110-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      K110-3 (CANH) - K110-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM
      K110-5 (CANH) - K110-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Airbag sensor assembly
      K110-6 (CANH) - K110-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Yaw rate sensor
      K110-9 (CANH) - K110-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Steering sensor
      K110-10 (CANH) - K110-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Skid control ECU assembly
      Result
      Result Proceed to
      OK A
      NG (Line to No. 1 CAN junction connector) B
      NG (Line to ECU or sensor) C
      NG (Line to ECM) 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

    GO TO STEP 11 Click here

    D

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

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


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

    2. Disconnect the K146 central gateway ECU (network gateway ECU) connector.

    3. B003YK5C24
      *a

      Front view of wire harness connector

      (to 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
      K146-18 (CA4H) - K146-17 (CA4L) Cable disconnected from negative (-) auxiliary 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 (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


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

    2. Disconnect the K3 combination meter assembly connector.

    3. B003YEAC21
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      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 (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

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


    1. Reconnect the K3 combination meter assembly connector.

    2. Disconnect the A78 ECM connector.

    3. B003XRUC15
      *a

      Front view of wire harness connector

      (to ECM)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A78-13 (CANH) - A78-26 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

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


    1. Reconnect the A78 ECM connector.

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

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

      B003YKYC28
      *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 Airbag Sensor Assembly
      *e to Yaw Rate Sensor *f to Skid Control ECU Assembly
      *g to Steering Sensor - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K109-1 (CANH) - K109-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 2 CAN junction connector
      K109-2 (CANH) - K109-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Combination meter assembly
      K109-4 (CANH) - K109-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Airbag sensor assembly
      K109-5 (CANH) - K109-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Yaw rate sensor
      K109-6 (CANH) - K109-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Skid control ECU assembly
      K109-7 (CANH) - K109-17 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Steering sensor
      Result
      Result Proceed to
      OK A
      NG (Line to No. 2 CAN junction connector) B
      NG (Line to ECU or sensor) C
      NG (Line to combination meter assembly) D

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 11 Click here

    D

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

    B

  10. 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.

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

      B003YKYC29
      *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 Hybrid Vehicle Control ECU Assembly *h to Certification ECU (Smart Key ECU Assembly)
      *i

      to Stereo Component Equalizer Assembly

      (w/ ASC System)

      		 *j to Power Steering ECU Assembly
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K110-1 (CANH) - K110-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 1 CAN junction connector
      K110-2 (CANH) - K110-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      K110-3 (CANH) - K110-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM
      K110-5 (CANH) - K110-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      K110-6 (CANH) - K110-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Air conditioning amplifier assembly
      K110-7 (CANH) - K110-17 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Hybrid vehicle control ECU assembly
      K110-8 (CANH) - K110-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      K110-9 (CANH) - K110-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Stereo component equalizer assembly*
      K110-10 (CANH) - K110-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Power steering ECU assembly

      • *: w/ ASC System

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

    D

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

    E

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

    C

  11. CHECK FOR SHORT IN CAN BUS LINES (ECU OR 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. B003Y3CC04
      *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
      K146-18 (CA4H) - K146-17 (CA4L) 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.

      • If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short in the wire harness and repair or replace the wire harness or connector if necessary.

      Result
      Result
      OK
      NG

    OK

    REPLACE ECU OR SENSOR

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


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

    2. Disconnect the K146 central gateway ECU (network gateway ECU) connector.

    3. B003YK5C24
      *a

      Front view of wire harness connector

      (to 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
      K146-18 (CA4H) - K146-17 (CA4L) Cable disconnected from negative (-) auxiliary 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 (NO. 2 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))