CAN COMMUNICATION SYSTEM Check Bus 1 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 23 (CA1H) of the network gateway ECU and terminal 16 (BAT) of the DLC3, or terminal 8 (CA1L) of the network gateway ECU and terminal 16 (BAT) of the DLC3.

Symptom Trouble Area
No resistance exists between terminal 23 (CA1H) of the network gateway ECU and terminal 16 (BAT) of the DLC3, or terminal 8 (CA1L) of the network gateway ECU and terminal 16 (BAT) of the DLC3.

  • Short in CAN main bus line

  • Short in CAN branch line

  • Clearance warning ECU assembly (w/ LEXUS Parking Assist-sensor System)

  • Parking assist ECU (w/ Panoramic View Monitor System)

  • Forward recognition camera (w/ Lexus Safety System +)

  • Millimeter wave radar sensor assembly (w/ Lexus Safety System +)

  • Front television camera assembly (w/ Panoramic View Monitor System)

  • Driving support ECU assembly (w/ Lexus Safety System +)

  • Side camera RH (outer rear view mirror assembly RH) (w/ Panoramic View Monitor System)

  • Side camera LH (outer rear view mirror assembly LH) (w/ Panoramic View Monitor System)

  • Rear television camera assembly (w/ Panoramic View Monitor System or Parking Assist Monitor System w/o Parallel Parking Assist Function)

  • Blind spot monitor sensor LH (w/ Blind Spot Monitor System)

  • Network gateway ECU

  • No. 3 CAN junction connector

  • No. 10 CAN junction connector

WIRING DIAGRAM

B005N21E09
B005P96E08

CAUTION / NOTICE / HINT

Note


  • 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

  • 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.

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  • 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), wait for at least 20 seconds, and then drive the vehicle at a speed of 36 km/h (22 mph) or more for 32 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.

    Click here

Tech Tips


  • Operating the engine switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE


  1. CHECK FOR SHORT TO +B IN CAN BUS LINE (NETWORK GATEWAY ECU)


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

    2. Disconnect the J75 network gateway ECU connector.

      B005ON4C02
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to Network Gateway ECU)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J75-23 (CA1H) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      J75-8 (CA1L) - J12-16 (BAT)
      Result
      Result
      OK
      NG

    OK

    REPLACE NETWORK GATEWAY ECU Click here

    NG

  2. CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 10 CAN JUNCTION CONNECTOR)


    1. Reconnect the J75 network gateway ECU connector.

    2. Disconnect the S56, S57, S58, S59 and S60 No. 10 CAN junction connectors.

      Tech Tips


      • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

      • Before disconnecting the connectors, make a note of where they are connected.

      • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

      B005M8EC01
      *1 DLC3 - -
      *a

      Rear view of wire harness connector

      (to No. 10 CAN Junction Connector)

      		 *b to Network Gateway ECU
      *c to No. 3 CAN Junction Connector *d

      to Blind Spot Monitor Sensor LH

      (w/ Blind Spot Monitor System)
      *e

      to Rear Television Camera Assembly

      (w/ Panoramic View Monitor System or Parking Assist Monitor System w/o Parallel Parking Assist Function)

      		 *f

      to Side Camera LH (Outer Rear View Mirror Assembly LH)

      (w/ Panoramic View Monitor System)
      Wiring Color:
      Code Color (CANH Side) Color (CANL Side) Connected to
      S56 G W Network gateway ECU
      S57 LG W No. 3 CAN junction connector
      S58 V W Blind spot monitor sensor LH
      S59 P W Rear television camera assembly
      S60 B W Side camera LH (outer rear view mirror assembly LH)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      S56-1 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Network gateway ECU
      S56-2 (CANL) - J12-16 (BAT)
      S57-1 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 3 CAN junction connector
      S57-2 (CANL) - J12-16 (BAT)
      S58-1 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Blind spot monitor sensor LH*1
      S58-2 (CANL) - J12-16 (BAT)
      S59-1 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Rear television camera assembly*2
      S59-2 (CANL) - J12-16 (BAT)
      S60-1 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Side camera LH (outer rear view mirror assembly LH)*3
      S60-2 (CANL) - J12-16 (BAT)
      *1: w/ Blind Spot Monitor System
      *2: w/ Panoramic View Monitor System or Parking Assist Monitor System w/o Parallel Parking Assist Function
      *3: w/ Panoramic View Monitor System
      Result
      Result Proceed to
      OK A
      NG (Network gateway ECU main line) B
      NG (ECU or sensor branch line) C
      NG (No. 3 CAN junction connector main line) D

    A

    REPLACE NO. 10 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NETWORK GATEWAY ECU - NO. 10 CAN JUNCTION CONNECTOR)

    C

    GO TO STEP 4 Click here

    D

  3. CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR)


    1. Reconnect the S56, S57, S58, S59 and S60 No. 10 CAN junction connectors.

    2. Disconnect the J95 No. 3 CAN junction connector.

      B005PHLC66
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to Network Gateway ECU
      *c

      to Parking Assist ECU

      (w/ Panoramic View Monitor System)

      		 *d

      to Clearance Warning ECU Assembly

      (w/ LEXUS Parking Assist-sensor System)
      *e

      to Millimeter Wave Radar Sensor Assembly

      (w/ Lexus Safety System +)

      		 *f

      to Front Television Camera Assembly

      (w/ Panoramic View Monitor System)
      *g

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)

      		 *h

      to Forward Recognition Camera

      (w/ Lexus Safety System +)
      *i

      to Side Camera RH (Outer Rear View Mirror Assembly RH)

      (w/ Panoramic View Monitor System)

      		 *j to No. 10 CAN Junction Connector

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      J95-1 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Network gateway ECU
      J95-11 (CANL) - J12-16 (BAT)
      J95-2 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Parking assist ECU*1
      J95-12 (CANL) - J12-16 (BAT)
      J95-3 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Clearance warning ECU assembly*3
      J95-13 (CANL) - J12-16 (BAT)
      J95-5 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Millimeter wave radar sensor assembly*2
      J95-15 (CANL) - J12-16 (BAT)
      J95-6 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Front television camera assembly*1
      J95-16 (CANL) - J12-16 (BAT)
      J95-7 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Driving support ECU assembly*2
      J95-17 (CANL) - J12-16 (BAT)
      J95-8 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Forward recognition camera*2
      J95-18 (CANL) - J12-16 (BAT)
      J95-9 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Side camera RH (outer rear view mirror assembly RH)*1
      J95-19 (CANL) - J12-16 (BAT)
      J95-10 (CANH) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 10 CAN junction connector
      J95-20 (CANL) - J12-16 (BAT)
      *1: w/ Panoramic View Monitor System
      *2: w/ Lexus Safety System +
      *3: w/ LEXUS Parking Assist-sensor System
      Result
      Result Proceed to
      OK A
      NG (No. 10 CAN junction connector main line) B
      NG (ECU or sensor branch line) C
      NG (Network gateway ECU main line) D

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 10 CAN JUNCTION CONNECTOR)

    D

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NETWORK GATEWAY ECU - NO. 3 CAN JUNCTION CONNECTOR)

    C

  4. CHECK FOR SHORT TO +B IN CAN BUS LINE (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 bus line shorted to +B is connected.

      Click here

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

      B005NNFC04
      *1 DLC3 - -
      *a

      Component with harness connected

      (Network Gateway ECU)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      J75-23 (CA1H) - J12-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      J75-8 (CA1L) - J12-16 (BAT)

      Tech Tips

      If the resistance changes to 6 kΩ or higher 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 CAN BUS LINE OR CONNECTOR