CAN COMMUNICATION SYSTEM Check Bus 1 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 23 (CA1H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 8 (CA1L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom Trouble Area
No resistance exists between terminal 23 (CA1H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 8 (CA1L) 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)

  • Millimeter wave radar sensor assembly

    (w/ Toyota Safety Sense)

  • Forward recognition camera

    (w/ Toyota Safety Sense)

  • Clearance warning ECU assembly

    (w/ TOYOTA Parking Assist-sensor System)

  • Blind spot monitor sensor LH

    (w/ Blind Spot Monitor System)

  • No. 1 CAN junction connector

  • No. 6 CAN junction connector

    (w/ Blind Spot Monitor System)

WIRING DIAGRAM


  1. w/o Blind Spot Monitor System

    B008LCPE05

  2. w/ Blind Spot Monitor System

    B008LCYE05

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 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 blind spot monitor system on using the blind spot monitor main switch (ON/OFF switch), turn the cruise control main switch on, turn the LDA main switch on and then drive the vehicle at a speed of 40 km/h (25 mph) or more for approximately 52 seconds 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
      w/o Blind Spot Monitor System A
      w/ Blind Spot Monitor System B

    B

    CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 6 CAN JUNCTION CONNECTOR) Click here

    A

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the No. 1 CAN junction connector.

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

      B008KKNC37
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b

      to Clearance Warning ECU Assembly

      (w/ TOYOTA Parking Assist-sensor System)
      *c

      to Forward Recognition Camera

      (w/ Toyota Safety Sense)

      		 *d

      to Millimeter Wave Radar Sensor Assembly

      (w/ Toyota Safety Sense)
      *e to Central Gateway ECU (Network Gateway ECU) - -
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F112-1 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*1
      F112-12 (CANL) - F41-4 (CG)
      F112-2 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Forward recognition camera*2
      F112-13 (CANL) - F41-4 (CG)
      F112-3 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*2
      F112-14 (CANL) - F41-4 (CG)
      F112-4 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      F112-15 (CANL) - F41-4 (CG)
      F112-5 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      F112-16 (CANL) - F41-4 (CG)

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

      • *2: w/ Toyota Safety Sense

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

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 8 Click here

    B

  3. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the F74 central gateway ECU (network gateway ECU) connector.

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

      B008KKNC38
      *1 DLC3 - -
      *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
      F112-4 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F112-15 (CANL) - F41-4 (CG)
      F112-5 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F112-16 (CANL) - F41-4 (CG)
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    B

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    C

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

  4. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 6 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the No. 6 CAN junction connector.

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

      B008KKNC31
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 6 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      *c to Blind Spot Monitor Sensor LH *d to No. 1 CAN Junction Connector
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      M92-1 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      M92-12 (CANL) - F41-4 (CG)
      M92-6 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Blind spot monitor sensor LH
      M92-17 (CANL) - F41-4 (CG)
      M92-11 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 1 CAN junction connector
      M92-22 (CANL) - F41-4 (CG)
      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. 6 CAN JUNCTION CONNECTOR

    C

    CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR) Click here

    D

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

    B

  5. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 6 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the F74 central gateway ECU (network gateway ECU) connector.

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

      B008KKNC32
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 6 CAN Junction Connector)

      		 *b to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition
      M92-1 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      M92-12 (CANL) - F41-4 (CG)
      Result
      Result Result
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    B

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    C

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 6 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

  6. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR)


    1. Disconnect the No. 1 CAN junction connector.

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

      B008KKNC39
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b

      to Clearance Warning ECU Assembly

      (w/ TOYOTA Parking Assist-sensor System)
      *c

      to Forward Recognition Camera

      (w/ Toyota Safety Sense)

      		 *d

      to Millimeter Wave Radar Sensor Assembly

      (w/ Toyota Safety Sense)
      *e to No. 6 CAN Junction Connector *f to Central Gateway ECU (Network Gateway ECU)
      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F112-1 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*1
      F112-12 (CANL) - F41-4 (CG)
      F112-2 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Forward recognition camera*2
      F112-13 (CANL) - F41-4 (CG)
      F112-3 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Millimeter wave radar sensor assembly*2
      F112-14 (CANL) - F41-4 (CG)
      F112-4 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 6 CAN junction connector
      F112-15 (CANL) - F41-4 (CG)
      F112-5 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      F112-16 (CANL) - F41-4 (CG)

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

      • *2: w/ Toyota Safety Sense

      Result
      Result Proceed to
      OK A
      NG (Line to central gateway ECU (network gateway ECU)) B
      NG (Line to No. 6 CAN junction connector) C
      NG (Line to ECU or sensor) D

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 6 CAN JUNCTION CONNECTOR)

    D

    GO TO STEP 8 Click here

    B

  7. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the F74 central gateway ECU (network gateway ECU) connector.

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

      B008KKNC40
      *1 DLC3 - -
      *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
      F112-5 (CANH) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F112-16 (CANL) - F41-4 (CG)
      Result
      Result Result
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    B

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    C

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

  8. 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.

      B008LY6C10
      *1 DLC3 - -
      *a

      Component with harness connected

      (Central Gateway ECU (Network Gateway ECU))

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      F74-23 (CA1H) - F41-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F74-8 (CA1L) - F41-4 (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