CAN COMMUNICATION SYSTEM(for LHD) Check Bus 5 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the bus 5 CAN main wires and/or CAN branch wires when the resistance between terminals 15 (CA5H) and 16 (CA5L) of the central gateway ECU is below 54 Ω.

Detection Item Trouble Area
Resistance between terminals 15 (CA5H) and 16 (CA5L) of central gateway ECU is below 54 Ω.

  • Short in bus 5 CAN main wires

  • Short in bus 5 CAN branch wires

  • Central gateway ECU

  • Power management control ECU

  • Absorber control ECU*1

  • Driving support ECU assembly*2

  • Forward recognition camera*2

  • Millimeter wave radar sensor assembly*2

  • Clearance warning ECU assembly*3

  • Blind spot monitor sensor RH*4

  • Headlight ECU sub-assembly LH

  • No. 4 CAN junction connector

  • No. 8 CAN junction connector

  • No. 9 CAN junction connector

WIRING DIAGRAM

B002BHHE06
B002BK8E03

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 power switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the power switch off, waiting time may be required before disconnecting the cable from the auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the auxiliary battery terminal notice before proceeding with work Click here.

  • After the repair, perform 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 power 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 IN CAN BUS WIRES (NO. 4 CAN JUNCTION CONNECTOR)


    1. Disconnect the No. 4 CAN junction connector.

      B002BETE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Central Gateway ECU
      *c to Absorber Control ECU (w/ Adaptive Variable Suspension System) *d to Power Management Control ECU
      *e to No. 9 CAN Junction Connector - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connect to
      N184-8 (CANH) - N184-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU
      N184-9 (CANH) - N184-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Absorber control ECU*
      N184-10 (CANH) - N184-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Power management control ECU
      N184-11 (CANH) - N184-22 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 9 CAN junction connector

      • *: w/ Adaptive Variable Suspension System

      Result
      Result Proceed to
      OK A
      NG (Central gateway ECU CAN main wire) B
      NG (No. 9 CAN junction connector CAN main wire) C
      NG (ECU or sensor CAN branch wires) D

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    C

    CONNECT CONNECTOR Click here

    D

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

    B

  2. CONNECT CONNECTOR


    1. Reconnect the N184 No. 4 CAN junction connector.


    NEXT

  3. CHECK FOR SHORT IN CAN BUS WIRES (CENTRAL GATEWAY ECU - NO. 4 CAN JUNCTION CONNECTOR)


    1. B002BGKE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Central Gateway ECU)

      Disconnect the central gateway ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      N176-15 (CA5H) - N176-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    OK

    REPLACE CENTRAL GATEWAY ECU Click here

    NG

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CENTRAL GATEWAY ECU - NO. 4 CAN JUNCTION CONNECTOR)

  4. CONNECT CONNECTOR


    1. Reconnect the N184 No. 4 CAN junction connector.


    NEXT

  5. CHECK FOR SHORT IN CAN BUS WIRES (NO. 9 CAN JUNCTION CONNECTOR)


    1. Disconnect the No. 9 CAN junction connector.

      B002BK0E01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to No. 9 CAN Junction Connector)

      		 *b to No. 8 CAN Junction Connector
      *c to No. 4 CAN Junction Connector *d Headlight ECU Sub-assembly LH
      *e to Driving Support ECU Assembly (w/ Pre-crash Safety System) *f to Clearance Warning ECU Assembly (w/ LEXUS Parking Assist-sensor System)
      *g to Forward Recognition Camera (w/ Pre-crash Safety System) *h to Millimeter Wave Radar Sensor Assembly (w/ Pre-crash Safety System)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connect to
      N131-3 (CANH) - N131-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 8 CAN junction connector
      N131-5 (CANH) - N131-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 4 CAN junction connector
      N131-7 (CANH) - N131-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Headlight ECU sub-assembly LH
      N131-8 (CANH) - N131-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Driving support ECU assembly*1
      N131-9 (CANH) - N131-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      N131-10 (CANH) - N131-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Forward recognition camera*1
      N131-11 (CANH) - N131-22 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*1

      • *1: w/ Pre-crash Safety System

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

      Result
      Result Proceed to
      OK A
      NG (No. 4 CAN junction connector CAN main wire) B
      NG (No. 8 CAN junction connector CAN main wire) C
      NG (ECU or sensor CAN branch wires) D

    A

    REPLACE NO. 9 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 9 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

    D

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

    C

  6. CONNECT CONNECTOR


    1. Reconnect the N131 No. 9 CAN junction connector.


    NEXT

  7. CHECK FOR SHORT IN CAN BUS WIRES (NO. 8 CAN JUNCTION CONNECTOR)

    B002BY2E01
    Text in Illustration
    *a

    Rear view of wire harness connector

    (to No. 8 CAN Junction Connector)

    		 *b to No. 9 CAN Junction Connector
    *c to Central Gateway ECU *d to Blind Spot Monitor Sensor RH (w/ Blind Spot Monitor System)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connect to
      T46-8 (CANH) - T46-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 9 CAN junction connector
      T46-9 (CANH) - T46-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU
      T46-10 (CANH) - T46-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Blind spot monitor sensor RH*

      • *: w/ Blind Spot Monitor System

      Result
      Result Proceed to
      OK A
      NG (No. 9 CAN junction connector CAN main wire) B
      NG (Central gateway ECU CAN main wire) C
      NG (ECU or sensor CAN branch wires) D

    A

    REPLACE NO. 8 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 8 CAN JUNCTION CONNECTOR - NO. 9 CAN JUNCTION CONNECTOR)

    D

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

    C

  8. CONNECT CONNECTOR


    1. Reconnect the T46 No. 8 CAN junction connector.


    NEXT

  9. CHECK FOR SHORT IN CAN BUS WIRES (CENTRAL GATEWAY ECU - NO. 8 CAN JUNCTION CONNECTOR)


    1. B002BF8E01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Central Gateway ECU)

      Disconnect the central gateway ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      N176-9 (CAXH) - N176-24 (CAXL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

    OK

    REPLACE CENTRAL GATEWAY ECU Click here

    NG

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (CENTRAL GATEWAY ECU - NO. 8 CAN JUNCTION CONNECTOR)

  10. CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR)


    1. B002C0WE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

      Reconnect the CAN junction connector.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited CAN branch wire is connected.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      N176-15 (CA5H) - N176-16 (CA5L) Cable disconnected from negative (-) auxiliary 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.


    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR CAN BRANCH WIRES OR CONNECTOR