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

  • Central gateway ECU (network gateway ECU)

  • Tire pressure warning ECU and receiver

    (w/ Tire Pressure Warning System and Tire Inflation Pressure Display Function)

  • Occupant detection ECU

    (w/ Occupant Classification System)

  • Brake actuator assembly

  • Rack and pinion power steering gear assembly

  • Steering sensor

  • Airbag sensor assembly

  • No. 2 CAN junction connector

  • No. 4 CAN junction connector

  • No. 3 junction connector

WIRING DIAGRAM

B00705LE05

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

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 ignition 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 ignition 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 ignition switch to ON and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 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

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. 3 JUNCTION CONNECTOR)


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

    2. Disconnect the R99 No. 3 junction connector.

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

      B006ZE9C40
      *a

      Front view of wire harness connector

      (to No. 3 Junction Connector)

      		 *b

      to Tire Pressure Warning ECU and Receiver

      (w/ Tire Pressure Warning System and Tire Inflation Pressure Display Function)
      *c

      to Occupant Detection ECU

      (w/ Occupant Classification System)

      		 *d to Central Gateway ECU (Network Gateway ECU)
      *e to No. 2 CAN Junction Connector - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      R99-8 (CANH) - R99-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Tire pressure warning ECU and receiver*1
      R99-9 (CANH) - R99-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Occupant detection ECU*2
      R99-10 (CANH) - R99-21 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      R99-11 (CANH) - R99-22 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction connector

      • *1: w/ Tire Pressure Warning System and Tire Inflation Pressure Display Function

      • *2: 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. 3 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. 3 JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the K76 central gateway ECU (network gateway ECU) connector.

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

      B007124C20
      *a

      Front view of wire harness connector

      (to No. 3 Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition
      R99-10 (CANH) - R99-21 (CANL) Cable disconnected from negative (-) 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. 3 JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


    1. Reconnect the R99 No. 3 junction connector.

    2. Disconnect the A67 No. 2 CAN junction connector.

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

      B007124C21
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b to Brake Actuator Assembly
      *c to No. 3 Junction Connector *d to Rack and Pinion Power Steering Gear Assembly
      *e to No. 4 CAN Junction Connector - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A67-1 (CANH) - A67-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Brake actuator assembly
      A67-2 (CANH) - A67-13 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 3 junction connector
      A67-4 (CANH) - A67-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Rack and pinion power steering gear assembly
      A67-5 (CANH) - A67-16 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 4 CAN junction connector
      Result
      Result Proceed to
      OK A
      NG (Line to No. 3 junction connector) B
      NG (Line to No. 4 CAN junction connector) 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. 3 JUNCTION CONNECTOR)

    D

    GO TO STEP 7 Click here

    C

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


    1. Reconnect the A67 No. 2 CAN junction connector.

    2. Disconnect the K128 No. 4 CAN junction connector.

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

      B007124C19
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Airbag Sensor Assembly
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K128-6 (CANH) - K128-17 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Airbag sensor assembly
      Result
      Result
      OK
      NG

    NG

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

    OK

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


    1. Reconnect the K128 No. 4 CAN junction connector.

    2. Disconnect the K127 No. 4 CAN junction connector.

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

      B007124C22
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to No. 2 CAN Junction Connector
      *c to Steering Sensor - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K127-6 (CANH) - K127-17 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction connector
      K127-7 (CANH) - K127-18 (CANL) Cable disconnected from negative (-) 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

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

    C

    GO TO STEP 7 Click here

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


    1. Disconnect the K73 airbag sensor assembly connector.

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

      B007124C19
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Airbag Sensor Assembly
      Standard Resistance
      Tester Connection Condition Specified Condition
      K128-6 (CANH) - K128-17 (CANL) Cable disconnected from negative (-) 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. 4 CAN JUNCTION CONNECTOR - AIRBAG SENSOR ASSEMBLY)

  7. 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. B006YJ9C15
      *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
      K76-22 (CA2H) - K76-7 (CA2L) 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.

      • 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