CAN COMMUNICATION SYSTEM Check Bus 3 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 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CA3H) and 21 (CA3L) of central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus lines

  • Short in CAN branch lines

  • Telematics transceiver (w/ Telematics Transceiver)

  • Radio receiver assembly (w/ Navigation System or Audio and Visual System)

  • Central gateway ECU (network gateway ECU)

  • Option connector (bus buffer ECU) (for LHD)

  • No. 7 CAN junction connector (for LHD)

  • No. 8 CAN junction connector (for RHD)

WIRING DIAGRAM

Figure 1. for LHD:

B003VNIE01

Figure 2. for RHD:

B003W8DE01

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 for at least 31 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 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 VEHICLE TYPE


    1. Check vehicle type.

      Result
      Result Proceed to
      for LHD A
      for RHD B

    B

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

    A

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


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

    2. Disconnect the K115 No. 7 CAN junction connector.

      B003WBWC80
      *a

      Front view of wire harness connector

      (to No. 7 CAN junction connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c

      to Telematics Transceiver

      (w/ Telematics Transceiver)

      		 *d

      to Radio Receiver Assembly

      (w/ Navigation System or Audio and Visual System)
      *e to Option Connector (Bus Buffer ECU) - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K115-7 (CANH) - K115-18 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      K115-8 (CANH) - K115-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Telematics transceiver*1
      K115-9 (CANH) - K115-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio receiver assembly*2
      K115-10 (CANH) - K115-21 (CANL) Cable disconnected from negative (-) battery terminal

      • 1 MΩ or higher*3

      • 200 Ω or higher*4

      		 Option connector (bus buffer ECU)
      K115-11 (CANH) - K115-22 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)

      • *1: w/ Telematics Transceiver

      • *2: w/ Navigation System or Audio and Visual System

      • *3: w/o CAN Compatible Optional Devices

      • *4: w/ CAN Compatible Optional Devices

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to ECU or sensor) C

    A

    REPLACE NO. 7 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 6 Click here

    B

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


    1. B003X08C22
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K141-6 (CA3H) - K141-21 (CA3L) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      K141-19 (CAYH) - K141-20 (CAYL) 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. 7 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


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

    2. Disconnect the K116 No. 8 CAN junction connector.

      B003WBWC81
      *a

      Front view of wire harness connector

      (to No. 8 CAN junction connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c

      to Radio Receiver Assembly

      (w/ Navigation System or Audio and Visual System)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K116-7 (CANH) - K116-18 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      K116-9 (CANH) - K116-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio receiver assembly*
      K116-11 (CANH) - K116-22 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)

      • *: w/ Navigation System or Audio and Visual System

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to ECU or sensor) C

    A

    REPLACE NO. 8 CAN JUNCTION CONNECTOR

    C

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

    B

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


    1. B003X08C22
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K141-6 (CA3H) - K141-21 (CA3L) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      K141-19 (CAYH) - K141-20 (CAYL) 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. 8 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

  6. 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. B003U8MC07
      *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
      K141-6 (CA3H) - K141-21 (CA3L) 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