CAN COMMUNICATION SYSTEM Check Bus 1 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 23 (CA1H) and 8 (CA1L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 23 (CA1H) and 8 (CA1L) 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)

  • Forward recognition camera

    (w/ Toyota Safety Sense)

  • Millimeter wave radar sensor assembly

    (w/ Toyota Safety Sense)

  • Blind spot monitor sensor RH

    (w/ Blind Spot Monitor System)

  • Rear television camera assembly

    (w/ Parking Assist Monitor System)

  • Clearance warning ECU assembly

    (w/ TOYOTA Parking Assist-sensor System)

  • No. 1 CAN junction connector

  • No. 5 CAN junction connector

WIRING DIAGRAM

B00862QE01

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 ignition 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 ignition 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

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 FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the A66 No. 1 CAN junction connector.

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

      B00861ZC04
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b

      to Millimeter Wave Radar Sensor Assembly

      (w/ Toyota Safety Sense)
      *c

      to Forward Recognition Camera

      (w/ Toyota Safety Sense)

      		 *d to Central Gateway ECU (Network Gateway ECU)
      *e to No. 5 CAN Junction Connector - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A66-1 (CANH) - A66-7 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*
      A66-2 (CANH) - A66-8 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Forward recognition camera*
      A66-3 (CANH) - A66-9 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      A66-5 (CANH) - A66-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 5 CAN junction connector

      • *: w/ Toyota Safety Sense

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to No. 5 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

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

    D

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

    B

  2. CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the K76 central gateway ECU (network gateway ECU) connector.

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

      B00880UC03
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition
      A66-3 (CANH) - A66-9 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

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


    1. Reconnect the A66 No. 1 CAN junction connector.

    2. Disconnect the R98 No. 5 CAN junction connector.

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

      B0085KJC14
      *a

      Front view of wire harness connector

      (to No. 5 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c

      to Clearance Warning ECU Assembly

      (w/ TOYOTA Parking Assist-sensor System)

      		 *d

      to Blind Spot Monitor Sensor RH

      (w/ Blind Spot Monitor System)
      *e

      to Rear Television Camera Assembly

      (w/ Parking Assist Monitor System)

      		 *f to No. 1 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      R98-1 (CANH) - R98-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU)
      R98-2 (CANH) - R98-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*1
      R98-3 (CANH) - R98-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Blind spot monitor sensor RH*2
      R98-4 (CANH) - R98-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Rear television camera assembly*3
      R98-5 (CANH) - R98-15 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 1 CAN junction connector

      • *1: w/ TOYOTA Parking Assist-sensor System

      • *2: w/ Blind Spot Monitor System

      • *3: w/ Parking Assist Monitor System

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to No. 1 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 5 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 5 CAN JUNCTION CONNECTOR - NO. 1 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 5 Click here

    B

  4. CHECK FOR SHORT IN CAN BUS LINES (NO. 5 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the K76 central gateway ECU (network gateway ECU) connector.

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

      B0085KJC03
      *a

      Front view of wire harness connector

      (to No. 5 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition
      R98-1 (CANH) - R98-11 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 5 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

  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. B0086ACC13
      *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
      K76-23 (CA1H) - K76-8 (CA1L) 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.

      • 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