CAN COMMUNICATION SYSTEM Check Bus 5 Line for Short to GND

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminal 15 (CA5H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 16 (CA5L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom Trouble Area
There is no resistance between terminal 15 (CA5H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 16 (CA5L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.
  • Short to +B in CAN main bus wire

  • Short to +B in CAN branch wire

  • Forward recognition camera*1

  • Driving support ECU assembly*1

  • Clearance warning ECU assembly*2

  • Millimeter wave radar sensor assembly*1

  • Central gateway ECU (network gateway ECU)

  • Parking assist ECU*3

  • Blind spot monitor sensor LH*4

  • Rear television camera assembly*5

  • Absorber control ECU*6

  • No. 3 CAN junction connector

  • No. 6 CAN junction connector

*1: w/ Pre-collision System
*2: w/ LEXUS Parking Assist-sensor System
*3: w/ Panoramic View Monitor System
*4: w/ Blind Spot Monitor System
*5: w/ Parking Assist Monitor System
*6: w/ Adaptive Variable Suspension System

WIRING DIAGRAM

B008ICDE02

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 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

  • Some parts must be initialized and set when replacing or removing and installing parts.

    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 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


  • Operating the engine switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • 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 GND IN CAN BUS WIRE (NO. 3 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the No. 3 CAN junction connector.

      B008HC9C11
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      *b to Central Gateway ECU (Network Gateway ECU)
      *c to Millimeter Wave Radar Sensor Assembly (w/ Pre-collision System) *d to Clearance Warning ECU Assembly (w/ LEXUS Parking Assist-sensor System)
      *e to Driving Support ECU Assembly (w/ Pre-collision System) *f to Forward Recognition Camera (w/ Pre-collision System)
      *g to No. 6 CAN Junction Connector *h Front view of DLC3
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I93-3 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      I93-13 (CANL) - I7-4 (CG)
      I93-4 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*1
      I93-14 (CANL) - I7-4 (CG)
      I93-6 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      I93-16 (CANL) - I7-4 (CG)
      I93-7 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Driving support ECU assembly*1
      I93-17 (CANL) - I7-4 (CG)
      I93-8 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Forward recognition camera*1
      I93-18 (CANL) - I7-4 (CG)
      I93-9 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 6 CAN junction connector
      I93-19 (CANL) - I7-4 (CG)
      *1: w/ Pre-collision System
      *2: w/ LEXUS Parking Assist-sensor System
      Result
      Result Proceed to
      OK A
      NG (Central gateway ECU [network gateway ECU] main wire) B
      NG (No. 6 CAN junction connector CAN main wire) C
      NG (Wire to ECU or sensor) D

    A
    C
    D
    B
  2. CONNECT CONNECTOR


    1. Reconnect the I95 No. 3 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT
  3. CHECK FOR SHORT TO GND IN CAN BUS WIRE (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 3 CAN JUNCTION CONNECTOR)


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

      B008IK3C27
      *a

      Front view of wire harness connector

      (to Central Gateway ECU [Network Gateway ECU])

      *b Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      I164-15 (CA5H) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I164-16 (CA5L) - I7-4 (CG)
      Result
      Proceed to
      OK
      NG

    OK
    NG
  4. CONNECT CONNECTOR


    1. Reconnect the I95 No. 3 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT
  5. CHECK FOR SHORT TO GND IN CAN BUS WIRE (NO. 6 CAN JUNCTION CONNECTOR)


    1. Disconnect the No. 6 CAN junction connector.

      B008HC9C12
      *a

      Front view of wire harness connector

      (to No. 6 CAN Junction Connector)

      *b to Parking Assist ECU (w/ Panoramic View Monitor System)
      *c to Blind Spot Monitor Sensor LH (w/ Blind Spot Monitor System) *d to Central Gateway ECU (Network Gateway ECU)
      *e to No. 3 CAN Junction Connector *f to Absorber Control ECU (w/ Adaptive Variable Suspension System)
      *g to Rear Television Camera Assembly (w/ Parking Assist Monitor System) *h Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I94-2 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Parking assist ECU*1
      I94-12 (CANL) - I7-4 (CG)
      I94-3 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Blind spot monitor sensor LH*2
      I94-13 (CANL) - I7-4 (CG)
      I94-4 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      I94-14 (CANL) - I7-4 (CG)
      I94-5 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 3 CAN junction connector
      I94-15 (CANL) - I7-4 (CG)
      I94-7 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Absorber control ECU*3
      I94-17 (CANL) - I7-4 (CG)
      I94-8 (CANH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Rear television camera assembly*1, *4
      I94-18 (CANL) - I7-4 (CG)
      *1: w/ Panoramic View Monitor System
      *2: w/ Blind Spot Monitor System
      *3: w/ Adaptive Variable Suspension System
      *4: w/ Parking Assist Monitor System
      Result
      Result Proceed to
      OK A
      NG (Central gateway ECU [network gateway ECU] main wire) B
      NG (No. 6 CAN junction connector CAN main wire) C
      NG (Wire to ECU or sensor) D

    A
    C
    D
    B
  6. CONNECT CONNECTOR


    1. Reconnect the Q32 No. 6 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT
  7. CHECK FOR SHORT TO GND IN CAN BUS WIRE (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 6 CAN JUNCTION CONNECTOR)


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

      B008IK3C28
      *a

      Front view of wire harness connector

      (to Central Gateway ECU [Network Gateway ECU])

      *b Front view of DLC3
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      I164-9 (CAXH) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I164-24 (CAXL) - I7-4 (CG)
      Result
      Proceed to
      OK
      NG

    OK
    NG
  8. CHECK FOR SHORT TO GND IN CAN BUS WIRE (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 GND is connected.

      Click here

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

      B008HBEC32
      *a

      Component with harness connected

      (Central Gateway ECU [Network Gateway ECU])

      *b Front view of DLC3
      Standard Resistance
      Tester Connection Condition Specified Condition
      I164-15 (CA5H) - I7-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I164-16 (CA5L) - I7-4 (CG)

      Tech Tips

      If the resistance changes to 200 Ω or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.

      Result
      Proceed to
      OK
      NG

    OK
    NG