CAN COMMUNICATION SYSTEM Check Bus 4 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 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom Trouble Area
There is no resistance between terminal 22 (CA2H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 7 (CA2L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

  • Short to ground in CAN main bus line

  • Short to ground in CAN branch line

  • Central gateway ECU (network gateway ECU)

  • Skid control ECU (brake actuator assembly)

  • Driving support ECU assembly

    (w/ Lexus Safety System +)

  • Front steering control ECU

  • Power steering ECU assembly

  • Absorber control ECU

  • Rear steering control ECU

  • No. 8 CAN junction connector

    (for RHD)

  • No. 10 CAN junction connector

    (for LHD)

  • No. 15 CAN junction connector

    (for LHD)

  • No. 16 CAN junction connector

    (for RHD)

  • No. 18 CAN junction connector

  • No. 3 CAN junction terminal

WIRING DIAGRAM

B00752GE03
B0073SME01
for LHD
*a Rear Steering Control ECU
*b No. 18 CAN Junction Connector
*c No. 3 CAN Junction Terminal
B007556E01
B0073SME04
for RHD
*a Rear Steering Control ECU
*b No. 18 CAN Junction Connector
*c No. 3 CAN Junction Terminal

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

  • 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


  • 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 TO GND IN CAN BUS LINE (NO. 16 CAN JUNCTION CONNECTOR) Click here

    A

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 15 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the O196 No. 15 CAN junction connector.

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

      B0076WSC29
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 15 CAN Junction Connector)

      		 *b to Skid Control ECU (Brake Actuator Assembly)
      *c to Central Gateway ECU (Network Gateway ECU) *d

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)
      *e to No. 10 CAN Junction Connector - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      O196-1 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      O196-12 (CANL) - O8-4 (CG)
      O196-2 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      O196-13 (CANL) - O8-4 (CG)
      O196-3 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Driving support ECU assembly*
      O196-14 (CANL) - O8-4 (CG)
      O196-4 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 10 CAN junction connector
      O196-15 (CANL) - O8-4 (CG)

      • *: w/ Lexus Safety System +

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to No. 10 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 15 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 10 CAN JUNCTION CONNECTOR) Click here

    D

    GO TO STEP 12 Click here

    B

  3. CHECK FOR SHORT TO GND IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the O157 central gateway ECU (network gateway ECU) connector.

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

      B00756YC12
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      O157-22 (CA2H) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      O157-7 (CA2L) - O8-4 (CG)
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - NO. 15 CAN JUNCTION CONNECTOR)

  4. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 10 CAN JUNCTION CONNECTOR)


    1. Disconnect the T32 No. 10 CAN junction connector.

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

      B0076WSC15
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 10 CAN Junction Connector)

      		 *b to Front Steering Control ECU
      *c to Power Steering ECU Assembly *d to No. 18 CAN Junction Connector
      *e to Absorber Control ECU *f to No. 15 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      T32-1 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Front steering control ECU
      T32-12 (CANL) - O8-4 (CG)
      T32-2 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      T32-13 (CANL) - O8-4 (CG)
      T32-3 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 18 CAN junction connector
      T32-14 (CANL) - O8-4 (CG)
      T32-4 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Absorber control ECU
      T32-15 (CANL) - O8-4 (CG)
      T32-5 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 15 CAN junction connector
      T32-16 (CANL) - O8-4 (CG)
      Result
      Result Proceed to
      OK A
      NG (Line to No. 18 CAN junction connector) B
      NG (Line to No. 15 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 10 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 10 CAN JUNCTION CONNECTOR - NO. 15 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 12 Click here

    B

  5. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 18 CAN JUNCTION CONNECTOR)


    1. Disconnect the U61 No. 18 CAN junction connector.

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

      B0076WSC30
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 18 CAN Junction Connector)

      		 *b to No. 10 CAN Junction Connector
      *c to No. 3 CAN Junction Terminal *d to Rear Steering Control ECU
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      U61-5 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 10 CAN junction connector
      U61-16 (CANL) - O8-4 (CG)
      U61-6 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 3 CAN junction terminal
      U61-17 (CANL) - O8-4 (CG)
      U61-7 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Rear steering control ECU
      U61-18 (CANL) - O8-4 (CG)
      Result
      Result Proceed to
      OK A
      NG (Line to No. 3 CAN junction terminal) B
      NG (Line to No. 10 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 18 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 18 CAN JUNCTION CONNECTOR - NO. 10 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 12 Click here

    B

  6. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION TERMINAL)


    1. Disconnect the U55 No. 3 CAN junction terminal connector.

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

      B0072N0C02
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Terminal)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      U55-3 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      U55-2 (CANL) - O8-4 (CG)
      Result
      Result
      OK
      NG

    OK

    REPLACE NO. 3 CAN JUNCTION TERMINAL

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION TERMINAL - NO. 18 CAN JUNCTION CONNECTOR)

  7. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 16 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the T37 No. 16 CAN junction connector.

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

      B0076WSC31
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 16 CAN Junction Connector)

      		 *b to Skid Control ECU (Brake Actuator Assembly)
      *c to Absorber Control ECU *d to No. 8 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      T37-1 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      T37-12 (CANL) - O8-4 (CG)
      T37-2 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Absorber control ECU
      T37-13 (CANL) - O8-4 (CG)
      T37-3 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 8 CAN junction connector
      T37-14 (CANL) - O8-4 (CG)
      Result
      Result Proceed to
      OK A
      NG (Line to No. 8 CAN junction connector) B
      NG (Line to ECU or sensor) C

    A

    REPLACE NO. 16 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 12 Click here

    B

  8. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 8 CAN JUNCTION CONNECTOR)


    1. Disconnect the O110 No. 8 CAN junction connector.

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

      B0076WSC32
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 8 CAN Junction Connector)

      		 *b to Front Steering Control ECU
      *c to Power Steering ECU Assembly *d to No. 18 CAN Junction Connector
      *e to Central Gateway ECU (Network Gateway ECU) *f

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)
      *g to No. 16 CAN Junction Connector - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      O110-1 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Front steering control ECU
      O110-12 (CANL) - O8-4 (CG)
      O110-2 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      O110-13 (CANL) - O8-4 (CG)
      O110-3 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 18 CAN junction connector
      O110-14 (CANL) - O8-4 (CG)
      O110-4 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      O110-15 (CANL) - O8-4 (CG)
      O110-5 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Driving support ECU assembly*
      O110-16 (CANL) - O8-4 (CG)
      O110-6 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 16 CAN junction connector
      O110-17 (CANL) - O8-4 (CG)

      • *: w/ Lexus Safety System +

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to No. 18 CAN junction connector) C
      NG (Line to No. 16 CAN junction connector) D
      NG (Line to ECU or sensor) E

    A

    REPLACE NO. 8 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 18 CAN JUNCTION CONNECTOR) Click here

    D

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 8 CAN JUNCTION CONNECTOR - NO. 16 CAN JUNCTION CONNECTOR)

    E

    GO TO STEP 12 Click here

    B

  9. CHECK FOR SHORT TO GND IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the O157 central gateway ECU (network gateway ECU) connector.

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

      B00756YC12
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to Central Gateway ECU (Network Gateway ECU))

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      O157-22 (CA2H) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      O157-7 (CA2L) - O8-4 (CG)
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - NO. 8 CAN JUNCTION CONNECTOR)

  10. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 18 CAN JUNCTION CONNECTOR)


    1. Disconnect the U61 No. 18 CAN junction connector.

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

      B0076WSC38
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 18 CAN Junction Connector)

      		 *b to No. 8 CAN Junction Connector
      *c to No. 3 CAN Junction Terminal *d to Rear Steering Control ECU
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      U61-5 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 8 CAN junction connector
      U61-16 (CANL) - O8-4 (CG)
      U61-6 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 3 CAN junction terminal
      U61-17 (CANL) - O8-4 (CG)
      U61-7 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Rear steering control ECU
      U61-18 (CANL) - O8-4 (CG)
      Result
      Result Proceed to
      OK A
      NG (Line to No. 3 CAN junction terminal) B
      NG (Line to No. 8 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 18 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 18 CAN JUNCTION CONNECTOR - NO. 8 CAN JUNCTION CONNECTOR)

    D

    CHECK FOR SHORT TO GND IN CAN BUS LINE (ECU OR SENSOR) Click here

    B

  11. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION TERMINAL)


    1. Disconnect the U55 No. 3 CAN junction terminal connector.

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

      B0072N0C02
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Terminal)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      U55-3 (CANH) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      U55-2 (CANL) - O8-4 (CG)
      Result
      Result
      OK
      NG

    OK

    REPLACE NO. 3 CAN JUNCTION TERMINAL

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION TERMINAL - NO. 18 CAN JUNCTION CONNECTOR)

  12. CHECK FOR SHORT TO GND IN CAN BUS LINE (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 bus line shorted to GND is connected.

      Click here

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

      B007487C34
      *1 DLC3 - -
      *a

      Component with harness connected

      (Central Gateway ECU (Network Gateway ECU))

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      O157-22 (CA2H) - O8-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      O157-7 (CA2L) - O8-4 (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.

      • If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short to ground 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