CAN COMMUNICATION SYSTEM Check Bus 2 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 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3.

Symptom Trouble Area
No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 4 (CG) of the DLC3, or terminal 17 (CA4L) 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

  • Combination meter assembly

  • Power steering ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Steering sensor

  • Airbag sensor assembly

  • ECM

  • Skid control ECU (brake actuator assembly)

  • Air conditioning amplifier assembly

  • Central gateway ECU (network gateway ECU)

  • 4WD ECU assembly

    (for AWD)

  • Headlight leveling ECU assembly

    (w/ Automatic Headlight Beam Level Control System)

  • Certification ECU (smart key ECU assembly)

    (w/ Smart Entry and Start System)

  • Clearance warning ECU assembly

    (w/ Toyota Parking Assist-sensor System)

  • No. 3 CAN junction connector

  • No. 4 CAN junction connector

WIRING DIAGRAM

A0027IFE02
A0027RWE02
A002C8UE01
A0028DBE01

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 ignition switch to ON and wait at least 60 seconds, and then drive the vehicle at a speed of 60 km/h (37 mph) or more for 9 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.

    Click here

  • If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.*


    • *: w/ Smart Entry and Start System

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 TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR) Click here

    A

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the F102 No. 3 CAN junction connector.

      A0028IUC82
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to No. 4 CAN Junction Connector
      *c to ECM *d to Steering Sensor
      *e to Power Steering ECU Assembly *f to Main Body ECU (Multiplex Network Body ECU)
      *g

      to 4WD ECU Assembly

      (for AWD)

      		 *h

      to Headlight Leveling ECU Assembly

      (w/ Automatic Headlight Beam Level Control System)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F102-1 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 4 CAN junction connector
      F102-11 (CANL) - F25-4 (CG)
      F102-2 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher ECM
      F102-12 (CANL) - F25-4 (CG)
      F102-4 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      F102-14 (CANL) - F25-4 (CG)
      F102-5 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      F102-15 (CANL) - F25-4 (CG)
      F102-6 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      F102-16 (CANL) - F25-4 (CG)
      F102-8 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher 4WD ECU assembly*1
      F102-18 (CANL) - F25-4 (CG)
      F102-9 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Headlight leveling ECU assembly*2
      F102-19 (CANL) - F25-4 (CG)

      • *1: for AWD

      • *2: w/ Automatic Headlight Beam Level Control System

      Result
      Result Proceed to
      OK A
      NG (No. 4 CAN junction connector main line) B
      NG (ECU or sensor bus line) C

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 4 Click here

    B

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


    1. Reconnect the F102 No. 3 CAN junction connector.

    2. Disconnect the F103 No. 4 CAN junction connector.

      A0028IUC83
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (No. 4 CAN Junction Connector)

      		 *b to No. 3 CAN Junction Connector
      *c to Skid Control ECU (Brake Actuator Assembly) *d to Air Conditioning Amplifier Assembly
      *e to Airbag Sensor Assembly *f

      to Certification ECU (Smart Key ECU Assembly)

      (w/ Smart Entry and Start System)
      *g to Combination Meter Assembly *h

      to Clearance Warning ECU Assembly

      (w/ Toyota Parking Assist-sensor System)
      *i to Central Gateway ECU (Network Gateway ECU) - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F103-1 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 3 CAN junction connector
      F103-11 (CANL) - F25-4 (CG)
      F103-2 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      F103-12 (CANL) - F25-4 (CG)
      F103-3 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      F103-13 (CANL) - F25-4 (CG)
      F103-4 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      F103-14 (CANL) - F25-4 (CG)
      F103-7 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)*1
      F103-17 (CANL) - F25-4 (CG)
      F103-8 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Combination meter assembly
      F103-18 (CANL) - F25-4 (CG)
      F103-9 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      F103-19 (CANL) - F25-4 (CG)
      F103-10 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      F103-20 (CANL) - F25-4 (CG)

      • *1: w/ Smart Entry and Start System

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

      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor bus line) C
      NG (Central gateway ECU (network gateway ECU) branch line) D

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

    D

    CHECK FOR SHORT TO GND IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

    C

  4. 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.

      A002CN9C94
      *1 DLC3 - -
      *a

      Component with harness connected

      (Central Gateway ECU (Network Gateway ECU))

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      F127-18 (CA4H) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F127-17 (CA4L) - F25-4 (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 CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINE OR CONNECTOR

  5. CHECK FOR SHORT TO GND IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the F127 central gateway ECU (network gateway ECU) connector.

    2. A002C0MC38
      *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
      F127-18 (CA4H) - F127-10 (GND) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F127-17 (CA4L) - F127-10 (GND)
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

  6. CHECK FOR SHORT TO GND IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the F102 No. 3 CAN junction connector.

      A0028IUC87
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to No. 4 CAN Junction Connector
      *c to ECM *d to Air Conditioning Amplifier Assembly
      *e to Airbag Sensor Assembly *f

      to Clearance Warning ECU Assembly

      (w/ Toyota Parking Assist-sensor System)
      *g to Main Body ECU (Multiplex Network Body ECU) *h

      to Certification ECU (Smart Key ECU Assembly)

      (w/ Smart Entry and Start System)
      *i

      to 4WD ECU Assembly

      (for AWD)

      		 *j to Central Gateway ECU (Network Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F102-1 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 4 CAN junction connector
      F102-11 (CANL) - F25-4 (CG)
      F102-2 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher ECM
      F102-12 (CANL) - F25-4 (CG)
      F102-3 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      F102-13 (CANL) - F25-4 (CG)
      F102-4 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      F102-14 (CANL) - F25-4 (CG)
      F102-5 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*1
      F102-15 (CANL) - F25-4 (CG)
      F102-6 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      F102-16 (CANL) - F25-4 (CG)
      F102-7 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)*2
      F102-17 (CANL) - F25-4 (CG)
      F102-8 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher 4WD ECU assembly*3
      F102-18 (CANL) - F25-4 (CG)
      F102-10 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      F102-20 (CANL) - F25-4 (CG)

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

      • *2: w/ Smart Entry and Start System

      • *3: for AWD

      Result
      Result Proceed to
      OK A
      NG (No. 4 CAN junction connector main line) B
      NG (ECU or sensor bus line) C
      NG (Central gateway ECU (network gateway ECU) branch line) D

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 9 Click here

    D

    CHECK FOR SHORT TO GND IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

    B

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


    1. Reconnect the F102 No. 3 CAN junction connector.

    2. Disconnect the F103 No. 4 CAN junction connector.

      A0028IUC85
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (No. 4 CAN Junction Connector)

      		 *b to No. 3 CAN Junction Connector
      *c to Skid Control ECU (Brake Actuator Assembly) *d to Steering Sensor
      *e to Power Steering ECU Assembly *f to Combination Meter Assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F103-1 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher No. 3 CAN junction connector
      F103-11 (CANL) - F25-4 (CG)
      F103-2 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      F103-12 (CANL) - F25-4 (CG)
      F103-4 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      F103-14 (CANL) - F25-4 (CG)
      F103-5 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      F103-15 (CANL) - F25-4 (CG)
      F103-8 (CANH) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Combination meter assembly
      F103-18 (CANL) - F25-4 (CG)
      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor bus line) C

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 4 CAN JUNCTION CONNECTOR)

    C

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

  8. CHECK FOR SHORT TO GND IN CAN BUS LINE (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Disconnect the F127 central gateway ECU (network gateway ECU) connector.

    2. A002C0MC38
      *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
      F127-18 (CA4H) - F127-10 (GND) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F127-17 (CA4L) - F127-10 (GND)
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

    REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))

  9. 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.

      A002CN9C94
      *1 DLC3 - -
      *a

      Component with harness connected

      (Central Gateway ECU (Network Gateway ECU))

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      F127-18 (CA4H) - F25-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      F127-17 (CA4L) - F25-4 (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 CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINE OR CONNECTOR