CAN COMMUNICATION SYSTEM(w/ Central Gateway ECU) Check Bus 2 Lines for Short Circuit (LHD Models)

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)

  • Hybrid vehicle control ECU

  • ECM

  • Main body ECU (multiplex network body ECU)

  • Combination meter sub-assembly

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

  • Spiral cable with sensor sub-assembly (steering angle sensor)

  • Air conditioning amplifier assembly

  • Power steering ECU assembly

  • Airbag ECU assembly

  • Transmission control ECU assembly

  • Certification ECU (smart key ECU assembly)

  • No. 1 CAN junction connector

  • No. 2 CAN junction connector

  • No. 3 CAN junction connector

WIRING DIAGRAM

B005XCFE02
B005YN7E02

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 system on using the cruise control switch (ON/OFF switch), wait at least 60 seconds, and then drive the vehicle at a speed of 50 km/h (31 mph) or more for at least 1.72 seconds.

  • 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


  • 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 FOR SHORT IN CAN BUS LINES (ECM)


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

    2. B005YVYE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A57 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A57-13 (CANH) - A57-5 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE ECM Click here

    NG

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


    1. Reconnect the A57 ECM connector.

    2. B005Z3QE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Combination Meter Sub-assembly)

      Disconnect the L27 combination meter sub-assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L27-19 (CANH) - L27-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE COMBINATION METER SUB-ASSEMBLY Click here

    NG

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


    1. Reconnect the L27 combination meter sub-assembly connector.

    2. B005ZE5E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)
      *b to No. 3 CAN Junction Connector
      *c to No. 1 CAN Junction Connector
      *d to Certification ECU (Smart Key ECU Assembly)
      *e to Spiral Cable with Sensor Sub-assembly (Steering Angle Sensor)

      Disconnect the L94 wire harness connector from the No. 2 CAN junction connector (instrument panel connector holder left side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      L94-2 (CANH) - L94-1 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 3 CAN junction connector
      L94-5 (CANH) - L94-4 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 1 CAN junction connector
      L94-8 (CANH) - L94-7 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Certification ECU (Smart key ECU assembly)
      L94-11 (CANH) - L94-10 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Spiral cable with sensor sub-assembly (Steering angle sensor)
      Result
      Result Proceed to
      OK A
      NG (Line to No. 1 CAN junction connector) B
      NG (Line to No. 3 CAN junction connector) C
      NG (Line to ECU or sensor) D

    B

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

    C

    CHECK FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR) Click here

    D

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

    A

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


    1. B005Z7FE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)
      *b to Power Steering ECU Assembly
      *c to Air Conditioning Amplifier Assembly
      *d to Airbag ECU Assembly
      *e to Central Gateway ECU (Network Gateway ECU)

      Disconnect the L95 wire harness connector from the No. 2 CAN junction connector (instrument panel connector holder right side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      L95-2 (CANH) - L95-3 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Power steering ECU assembly
      L95-5 (CANH) - L95-6 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Air conditioning amplifier assembly
      L95-8 (CANH) - L95-9 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Airbag ECU assembly
      L95-11 (CANH) - L95-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)

    OK

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    NG

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

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


    1. B005YMEE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)
      *b to Main Body ECU (Multiplex Network Body ECU)
      *c to No. 2 CAN Junction Connector

      Disconnect the L132 wire harness connector from the No. 1 CAN junction connector (instrument panel wire side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      L132-5 (CANH) - L132-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Main body ECU (Multiplex network body ECU)
      L132-6 (CANH) - L132-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher No. 2 CAN junction connector
      Result
      Result Proceed to
      OK A
      NG (Line to No. 2 CAN junction connector) B
      NG (Line to ECU or sensor) C

    B

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

    C

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

    A

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


    1. Disconnect the A67 wire harness connector from the No. 1 CAN junction connector (engine room main wire side).

    2. B005XDGE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)
      *b to ECM
      *c to Brake Booster with Master Cylinder Assembly (Skid Control ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A67-1 (CANH) - A67-7 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM
      A67-2 (CANH) - A67-8 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Brake booster with master cylinder assembly (Skid control ECU)
      Result
      Result Proceed to
      OK A
      NG (Line to ECM) B
      NG (Line to ECU or sensor) C

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    B

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

    C

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

  7. CHECK FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR)


    1. B005Y41E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)
      *b to Hybrid Vehicle Control ECU
      *c to No. 2 CAN Junction Connector
      *d to Combination Meter Sub-assembly

      Disconnect the L133 wire harness connector from the No. 3 CAN junction connector (instrument panel wire side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      L133-4 (CANH) -L133-10 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Hybrid vehicle control ECU
      L133-5 (CANH) - L133-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher No. 2 CAN junction connector
      L133-6 (CANH) - L133-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Combination meter sub-assembly
      Result
      Result Proceed to
      OK A
      NG (Line to No. 2 CAN junction connector) B
      NG (Line to combination meter subassembly) C
      NG (Line to ECU or sensor) D

    B

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - COMBINATION METER SUB-ASSEMBLY)

    D

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

    A

  8. CHECK FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR)


    1. B005Y9PE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)
      *b to Transmission Control ECU Assembly

      Disconnect the A68 wire harness connector from the No. 3 CAN junction connector (engine room main wire side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A68-1 (CANH) - A68-7 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    OK

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    NG

  9. 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. B005XG3E02
      Text in Illustration
      *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
      L192-18 (CA4H) - L192-17 (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 (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, repair or replace the short circuited branch line or connector.


    OK

    REPLACE ECU OR SENSOR

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR