CAN COMMUNICATION SYSTEM Check Bus 5 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the bus CAN main bus lines and/or CAN branch lines when the resistance between terminals 15 (CA5H) and 16 (CA5L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 15 (CA5H) and 16 (CA5L) of 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)

  • Absorber control ECU (w/ AVS System)

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

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

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

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

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

  • No. 2 CAN junction terminal

  • No. 9 CAN junction connector

  • No. 10 CAN junction connector

  • No. 13 CAN junction connector

WIRING DIAGRAM

Figure 1. for LHD:

B003T9JE01
B003U0OE01

Figure 2. for RHD:

B003VJDE01
B003U0OE02

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 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

  • Before replacing the main body ECU (multiplex network body ECU) or certification ECU (smart key ECU assembly), refer to Service Bulletin.

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. 10 CAN JUNCTION CONNECTOR) Click here

    A

  2. CHECK FOR SHORT IN CAN BUS LINES (NO. 10 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the K146, K147, K148, K149, K150 and K151 No. 10 CAN junction connectors.

      B003VGJC01
      *a

      Rear view of wire harness connector

      (to No. 10 CAN Junction Connector)

      		 *b to No. 9 CAN Junction Connector
      *c

      to Forward Recognition Camera

      (w/ Lexus Safety System +)

      		 *d

      to Millimeter Wave Radar Sensor Assembly

      (w/ Lexus Safety System +)
      *e

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)

      		 *f

      to Clearance Warning ECU Assembly

      (w/ LEXUS Parking Assist-sensor System)
      *g to No. 13 CAN Junction Connector - -
      Wiring Color:
      Code Color (CANH Side) Color (CANL Side) Connected to
      K146 LG B No. 9 CAN junction connector
      K147 R B Forward recognition camera
      K148 L B Millimeter wave radar sensor assembly
      K149 G B Driving support ECU assembly
      K150 P B Clearance warning ECU assembly
      K151 BE B No. 13 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
      K146-1 (CANH) - K146-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 9 CAN junction connector
      K147-1 (CANH) - K147-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Forward recognition camera*1
      K148-1 (CANH) - K148-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*1
      K149-1 (CANH) - K149-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Driving support ECU assembly*1
      K150-1 (CANH) - K150-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      K151-1 (CANH) - K151-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 13 CAN junction connector

      • *1: w/ Lexus Safety System +

      • *2: w/ LEXUS Parking Assist-sensor System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 9 CAN junction connector) B
      NG (Line to No. 13 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 10 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT IN CAN BUS LINES (NO. 13 CAN JUNCTION CONNECTOR) Click here

    D

    GO TO STEP 11 Click here

    B

  3. CHECK FOR SHORT IN CAN BUS LINES (NO. 9 CAN JUNCTION CONNECTOR)


    1. Reconnect the K146, K147, K148, K149, K150 and K151 No. 10 CAN junction connectors.

    2. Disconnect the K142, K143 and K144 No. 9 CAN junction connectors.

      B003TO0C02
      *a

      Rear view of wire harness connector

      (to No. 9 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c to No. 10 CAN Junction Connector *d

      to Absorber Control ECU

      (w/ AVS System)
      Wiring Color:
      Code Color (CANH Side) Color (CANL Side) Connected to
      K142 GR B Central gateway ECU (network gateway ECU)
      K143 LG B No. 10 CAN junction connector
      K144 SB B Absorber control ECU

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K142-1 (CANH) - K142-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      K143-1 (CANH) - K143-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 10 CAN junction connector
      K144-1 (CANH) - K144-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Absorber control ECU*

      • *: w/ AVS 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. 9 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 9 CAN JUNCTION CONNECTOR - NO. 10 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 11 Click here

    B

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


    1. Reconnect the K142, K143 and K144 No. 9 CAN junction connectors.

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

    3. B003VK4C25
      *a

      Front view of wire harness connector

      (to 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
      K141-15 (CA5H) - K141-16 (CA5L) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - NO. 9 CAN JUNCTION CONNECTOR)

  5. CHECK FOR SHORT IN CAN BUS LINES (NO. 13 CAN JUNCTION CONNECTOR)


    1. Reconnect the K146, K147, K148, K149, K150 and K151 No. 10 CAN junction connectors.

    2. B003UMPC04
      *a

      Front view of wire harness connector

      (to No. 13 CAN Junction Connector)
      *b to No. 10 CAN Junction Connector
      *c to No. 2 CAN Junction Terminal
      *d

      to Blind Spot Monitor Sensor LH

      (w/ Blind Spot Monitor System)

      Disconnect the Q68 No. 13 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
      Q68-3 (CANH) - Q68-9 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 10 CAN junction connector
      Q68-4 (CANH) - Q68-10 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction terminal
      Q68-5 (CANH) - Q68-11 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Blind spot monitor sensor LH*

      • *: w/ Blind Spot Monitor System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 10 CAN junction connector) B
      NG (Line to No. 2 CAN junction terminal) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 13 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 10 CAN JUNCTION CONNECTOR - NO. 13 CAN JUNCTION CONNECTOR)

    C

    GO TO STEP 10 Click here

    D

    GO TO STEP 11 Click here

  6. CHECK FOR SHORT IN CAN BUS LINES (NO. 10 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the K146, K147, K148, K150 and K151 No. 10 CAN junction connectors.

      B003WGWC01
      *a

      Rear view of wire harness connector

      (to No. 10 CAN Junction Connector)

      		 *b to No. 9 CAN Junction Connector
      *c

      to Forward Recognition Camera

      (w/ Lexus Safety System +)

      		 *d

      to Millimeter Wave Radar Sensor Assembly

      (w/ Lexus Safety System +)
      *e

      to Clearance Warning ECU Assembly

      (w/ LEXUS Parking Assist-sensor System)

      		 *f to No. 13 CAN Junction Connector
      Wiring Color:
      Code Color (CANH Side) Color (CANL Side) Connected to
      K146 LG B No. 9 CAN junction connector
      K147 R B Forward recognition camera
      K148 L B Millimeter wave radar sensor assembly
      K150 P B Clearance warning ECU assembly
      K151 BE B No. 13 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
      K146-1 (CANH) - K146-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 9 CAN junction connector
      K147-1 (CANH) - K147-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Forward recognition camera*1
      K148-1 (CANH) - K148-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*1
      K150-1 (CANH) - K150-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      K151-1 (CANH) - K151-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 13 CAN junction connector

      • *1: w/ Lexus Safety System +

      • *2: w/ LEXUS Parking Assist-sensor System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 9 CAN junction connector) B
      NG (Line to No. 13 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 10 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT IN CAN BUS LINES (NO. 13 CAN JUNCTION CONNECTOR) Click here

    D

    GO TO STEP 11 Click here

    B

  7. CHECK FOR SHORT IN CAN BUS LINES (NO. 9 CAN JUNCTION CONNECTOR)


    1. Reconnect the K146, K147, K148, K150 and K151 No. 10 CAN junction connectors.

    2. Disconnect the K142, K143 K144 and K157 No. 9 CAN junction connectors.

      B003X87C01
      *a

      Rear view of wire harness connector

      (to No. 9 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c to No. 10 CAN Junction Connector *d

      to Absorber Control ECU

      (w/ AVS System)
      *e

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)

      		 - -
      Wiring Color:
      Code Color (CANH Side) Color (CANL Side) Connected to
      K142 GR B Central gateway ECU (network gateway ECU)
      K143 LG B No. 10 CAN junction connector
      K144 SB B Absorber control ECU
      K157 G B Driving support ECU assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      K142-1 (CANH) - K142-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      K143-1 (CANH) - K143-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 10 CAN junction connector
      K144-1 (CANH) - K144-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Absorber control ECU*1
      K157-1 (CANH) - K157-2 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Driving support ECU assembly*2

      • *1: w/ AVS System

      • *2: 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. 9 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 9 CAN JUNCTION CONNECTOR - NO. 10 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 11 Click here

    B

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


    1. Reconnect the K142, K143 K144 and K157 No. 9 CAN junction connectors.

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

    3. B003VK4C25
      *a

      Front view of wire harness connector

      (to 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
      K141-15 (CA5H) - K141-16 (CA5L) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - NO. 9 CAN JUNCTION CONNECTOR)

  9. CHECK FOR SHORT IN CAN BUS LINES (NO. 13 CAN JUNCTION CONNECTOR)


    1. Reconnect the K146, K147, K148, K150 and K151 No. 10 CAN junction connectors.

    2. B003UMPC04
      *a

      Front view of wire harness connector

      (to No. 13 CAN Junction Connector)
      *b to No. 10 CAN Junction Connector
      *c to No. 2 CAN Junction Terminal
      *d

      to Blind Spot Monitor Sensor LH

      (w/ Blind Spot Monitor System)

      Disconnect the Q68 No. 13 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
      Q68-3 (CANH) - Q68-9 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 10 CAN junction connector
      Q68-4 (CANH) - Q68-10 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 2 CAN junction terminal
      Q68-5 (CANH) - Q68-11 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Blind spot monitor sensor LH*

      • *: w/ Blind Spot Monitor System

      Result
      Result Proceed to
      OK A
      NG (Line to No. 10 CAN junction connector) B
      NG (Line to No. 2 CAN junction terminal) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 13 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 10 CAN JUNCTION CONNECTOR - NO. 13 CAN JUNCTION CONNECTOR)

    D

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

    C

  10. CHECK FOR SHORT IN CAN BUS LINES (NO. 2 CAN JUNCTION TERMINAL)


    1. Reconnect the Q68 No. 13 CAN junction connector.

    2. B003TLKC83
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Terminal)

      Disconnect the K107 No. 2 CAN junction terminal connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K107-3 (CANH) - K107-2 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE NO. 2 CAN JUNCTION TERMINAL

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 2 CAN JUNCTION TERMINAL - NO. 13 CAN JUNCTION CONNECTOR)

  11. 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. B003U8MC06
      *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
      K141-15 (CA5H) - K141-16 (CA5L) 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