CAN COMMUNICATION SYSTEM Check Bus 4 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 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 22 (CA2H) and 7 (CA2L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus lines

  • Short in CAN branch lines

  • ECM

  • Hybrid vehicle control ECU

  • Central gateway ECU (network gateway ECU)

  • Occupant detection ECU

    (w/ Occupant Classification System)

  • Brake booster with master cylinder assembly

  • Airbag sensor assembly

  • Steering sensor

  • Power steering ECU assembly

  • No. 2 CAN junction connector

  • No. 5 CAN junction connector

WIRING DIAGRAM

B006HJKE12
B006J1OE10

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 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

  • 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 approximately 61 seconds. Turn the blind spot monitor system on using the blind spot monitor main switch (ON/OFF switch), turn the cruise control main switch on, turn the speed limiter switch on, turn the lane departure alert main switch on and then drive the vehicle at a speed of 20 km/h (12 mph) or more for approximately 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 hybrid vehicle control ECU, 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 FOR SHORT IN CAN BUS LINES (NO. 5 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the I78 No. 5 CAN junction connector.

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

      B006J8YC50
      *a

      Front view of wire harness connector

      (to No. 5 CAN Junction Connector)

      		 *b to No. 2 CAN Junction Connector
      *c to Central Gateway ECU (Network Gateway ECU) *d to ECM
      *e to Hybrid Vehicle Control ECU *f

      to Occupant Detection ECU

      (w/ Occupant Classification System)
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I78-1 (CANH) - I78-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 2 CAN junction connector
      I78-2 (CANH) - I78-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      I78-3 (CANH) - I78-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher ECM
      I78-4 (CANH) - I78-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Hybrid vehicle control ECU
      I78-5 (CANH) - I78-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Occupant detection ECU*

      • *: w/ Occupant Classification System

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

    A

    REPLACE NO. 5 CAN JUNCTION CONNECTOR

    C

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

    D

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

    B

  2. CHECK FOR SHORT IN CAN BUS LINES (NO. 5 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the I62 central gateway ECU (network gateway ECU) connector.

    2. B006IVXC04
      *a

      Front view of wire harness connector

      (to No. 5 CAN Junction Connector)
      *b 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
      I78-2 (CANH) - I78-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 5 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


    1. Reconnect the I78 No. 5 CAN junction connector.

    2. Disconnect the I75 No. 2 CAN junction connector.

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

      B006J8YC51
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to No. 5 CAN Junction Connector
      *c to Airbag Sensor Assembly *d to Brake Booster with Master Cylinder Assembly
      *e to Steering Sensor *f to Power Steering ECU Assembly
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I75-7 (CANH) - I75-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 5 CAN junction connector
      I75-8 (CANH) - I75-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Airbag sensor assembly
      I75-9 (CANH) - I75-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Brake booster with master cylinder assembly
      I75-10 (CANH) - I75-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Steering sensor
      I75-11 (CANH) - I75-22 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Power steering ECU assembly
      Result
      Result Proceed to
      OK A
      NG (Line to No. 5 CAN junction connector) B
      NG (Line to Airbag sensor assembly) 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. 2 CAN JUNCTION CONNECTOR - NO. 5 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 5 Click here

    C

  4. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION CONNECTOR - AIRBAG SENSOR ASSEMBLY)


    1. Disconnect the I59 airbag sensor assembly connector.

    2. B006IVXC05
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)
      *b to Airbag Sensor Assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I75-8 (CANH) - I75-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 1 MΩ or higher
      Result
      Result
      OK
      NG

    OK

    REPLACE AIRBAG SENSOR ASSEMBLY Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - AIRBAG SENSOR ASSEMBLY)

  5. 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. B006IS4C98
      *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
      I62-22 (CA2H) - I62-7 (CA2L) 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