CAN COMMUNICATION SYSTEM Check Bus 5 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the 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 the 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)

  • Power management control ECU

  • Driving support ECU assembly

    (w/ Lexus Safety System +)

  • Millimeter wave radar sensor assembly

    (w/ Lexus Safety System +)

  • Forward recognition camera

    (w/ Lexus Safety System +)

  • Clearance warning ECU assembly

    (w/ LEXUS Parking Assist-sensor System)

  • Rear television camera assembly

    (w/ Parking Assist Monitor System (w/o Parallel Parking Assist Function))

  • CAN No. 4 junction connector

  • CAN No. 7 junction connector

    (w/ Parking Assist Monitor System (w/o Parallel Parking Assist Function))

WIRING DIAGRAM

Figure 1. for RHD or without Parking Assist Monitor System (w/o Parallel Parking Assist Function)

B001KJSE02

Figure 2. w/ Parking Assist Monitor System (w/o Parallel Parking Assist Function)

B001MDSE02
B001N7EE02

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 or any 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 negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

    Click here

  • 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 RHD or without Parking Assist Monitor System (w/o Parallel Parking Assist Function) A
      w/ Parking Assist Monitor System (w/o Parallel Parking Assist Function) B

    B

    CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 4 JUNCTION CONNECTOR) Click here

    A

  2. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 4 JUNCTION CONNECTOR)


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

    2. Disconnect the H191 CAN No. 4 junction connector.

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

      B001N49C25
      *a

      Front view of wire harness connector

      (to CAN No. 4 Junction Connector)

      		 *b

      to Millimeter Wave Radar Sensor Assembly

      (w/ Lexus Safety System +)
      *c

      to Forward Recognition Camera

      (w/ Lexus Safety System +)

      		 *d

      to Clearance Warning ECU Assembly

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

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)

      		 *f to Power Management Control ECU
      *g to Central Gateway ECU (Network Gateway ECU) - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H191-1 (CANH) - H191-7 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*1
      H191-2 (CANH) - H191-8 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Forward recognition camera*1
      H191-3 (CANH) - H191-9 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      H191-4 (CANH) - H191-10 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Driving support ECU assembly*1
      H191-5 (CANH) - H191-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Power management control ECU
      H191-6 (CANH) - H191-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)

      • *1: w/ Lexus Safety System +

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

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to power management control ECU) C
      NG (Line to ECU or sensor) D

    A

    REPLACE CAN NO. 4 JUNCTION CONNECTOR

    C

    CHECK FOR SHORT IN CAN BUS LINES (POWER MANAGEMENT CONTROL ECU - CAN NO. 4 JUNCTION CONNECTOR) Click here

    D

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

    B

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


    1. Reconnect the H191 CAN No. 4 junction connector.

    2. Disconnect the H188 central gateway ECU (network gateway ECU) connector.

    3. B001LE1C70
      *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
      H188-15 (CA5H) - H188-16 (CA5L) Cable disconnected from negative (-) auxiliary 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) - CAN NO. 4 JUNCTION CONNECTOR)

  4. CHECK FOR SHORT IN CAN BUS LINES (POWER MANAGEMENT CONTROL ECU - CAN NO. 4 JUNCTION CONNECTOR)


    1. Reconnect the H191 CAN No. 4 junction connector.

    2. Disconnect the H3 power management control ECU connector.

    3. B001MMHC48
      *a

      Front view of wire harness connector

      (to Power Management Control ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H3-34 (CA2H) - H3-35 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - CAN NO. 4 JUNCTION CONNECTOR)

  5. CHECK FOR SHORT IN CAN BUS LINES (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 short circuited branch line is connected.

      Click here

    3. B001LNQC40
      *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
      H188-15 (CA5H) - H188-16 (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.

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

  6. CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 4 JUNCTION CONNECTOR)


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

    2. Disconnect the H191 CAN No. 4 junction connector.

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

      B001N49C26
      *a

      Front view of wire harness connector

      (to CAN No. 4 Junction Connector)

      		 *b

      to Millimeter Wave Radar Sensor Assembly

      (w/ Lexus Safety System +)
      *c

      to Forward Recognition Camera

      (w/ Lexus Safety System +)

      		 *d

      to Clearance Warning ECU Assembly

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

      to Driving Support ECU Assembly

      (w/ Lexus Safety System +)

      		 *f to CAN No. 7 Junction Connector
      *g to Central Gateway ECU (Network Gateway ECU) - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H191-1 (CANH) - H191-7 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*1
      H191-2 (CANH) - H191-8 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Forward recognition camera*1
      H191-3 (CANH) - H191-9 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      H191-4 (CANH) - H191-10 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Driving support ECU assembly*1
      H191-5 (CANH) - H191-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω CAN No. 7 junction connector
      H191-6 (CANH) - H191-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)

      • *1: w/ Lexus Safety System +

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

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to CAN No. 7 junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE CAN NO. 4 JUNCTION CONNECTOR

    C

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

    D

    GO TO STEP 10 Click here

    B

  7. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) - CAN NO. 4 JUNCTION CONNECTOR)


    1. Reconnect the H191 CAN No. 4 junction connector.

    2. Disconnect the H188 central gateway ECU (network gateway ECU) connector.

    3. B001LE1C70
      *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
      H188-15 (CA5H) - H188-16 (CA5L) Cable disconnected from negative (-) auxiliary 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) - CAN NO. 4 JUNCTION CONNECTOR)

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


    1. Reconnect the H191 CAN No. 4 junction connector.

    2. Disconnect the P36 CAN No. 7 junction connector.

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

      B001N49C27
      *a

      Front view of wire harness connector

      (to CAN No. 7 Junction Connector)

      		 *b to CAN No. 4 Junction Connector
      *c

      to Rear Television Camera Assembly

      (w/ Parking Assist Monitor System (w/o Parallel Parking Assist Function))

      		 *d to Power Management Control ECU
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      P36-1 (CANH) - P36-7 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω CAN No. 4 junction connector
      P36-2 (CANH) - P36-8 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Rear television camera assembly*
      P36-3 (CANH) - P36-9 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Power management control ECU

      • *: w/ Parking Assist Monitor System (w/o Parallel Parking Assist Function)

      Result
      Result Proceed to
      OK A
      NG (Line to power management control ECU) B
      NG (Line to ECU or sensor) C

    A

    REPLACE CAN NO. 7 JUNCTION CONNECTOR

    C

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

    B

  9. CHECK FOR SHORT IN CAN BUS LINES (POWER MANAGEMENT CONTROL ECU - CAN NO. 7 JUNCTION CONNECTOR)


    1. Reconnect the P36 CAN No. 7 junction connector.

    2. Disconnect the H3 power management control ECU connector.

    3. B001MMHC48
      *a

      Front view of wire harness connector

      (to Power Management Control ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H3-34 (CA2H) - H3-35 (CA2L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - CAN NO. 7 JUNCTION CONNECTOR)

  10. CHECK FOR SHORT IN CAN BUS LINES (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 short circuited branch line is connected.

      Click here

    3. B001LNQC40
      *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
      H188-15 (CA5H) - H188-16 (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.

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