CAN COMMUNICATION SYSTEM Check Bus 2 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 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus lines

  • Short in CAN branch lines

  • 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 IN CAN BUS LINES (COMBINATION METER ASSEMBLY - NO. 4 CAN JUNCTION CONNECTOR) Click here

    A

  2. CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY - NO. 4 CAN JUNCTION CONNECTOR)


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

    2. A0029BPC83
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the F126 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F126-28 (CANH) - F126-27 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

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


    1. Reconnect the F126 combination meter assembly connector.

    2. A002ACMC02
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A43 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A43-13 (CANH) - A43-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK (for 1AR-FE) A
      OK (for 2GR-FKS) B
      NG C

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

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


    1. Reconnect the A43 ECM connector.

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

      A002AHIC06
      *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) - F102-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 4 CAN junction connector
      F102-2 (CANH) - F102-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      F102-4 (CANH) - F102-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      F102-5 (CANH) - F102-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      F102-6 (CANH) - F102-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      F102-8 (CANH) - F102-18 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher 4WD ECU assembly*1
      F102-9 (CANH) - F102-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Headlight leveling ECU assembly*2

      • *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 branch line) C
      NG (ECM main line) D

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 6 Click here

    D

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM - NO. 3 CAN JUNCTION CONNECTOR)

    B

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


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

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

      A002AHIC07
      *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) - F103-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 3 CAN junction connector
      F103-2 (CANH) - F103-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      F103-3 (CANH) - F103-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      F103-4 (CANH) - F103-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      F103-7 (CANH) - F103-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)*1
      F103-8 (CANH) - F103-18 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      F103-9 (CANH) - F103-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*2
      F103-10 (CANH) - F103-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)

      • *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 branch line) C
      NG (Central gateway ECU (network gateway ECU) branch line) D
      NG (Combination meter assembly main line) E

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

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

    D

    CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

    E

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 4 CAN JUNCTION CONNECTOR)

    C

  6. 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. A002BTZC08
      *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
      F127-18 (CA4H) - F127-17 (CA4L) 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 CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR

  7. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Reconnect the F103 No. 4 CAN junction connector.

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

    3. A002C0MC36
      *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) - F127-17 (CA4L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

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

  8. CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY - NO. 4 CAN JUNCTION CONNECTOR)


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

    2. A0029BPC83
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the F126 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F126-28 (CANH) - F126-27 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

  9. CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 3 CAN JUNCTION CONNECTOR)


    1. Reconnect the F126 combination meter assembly connector.

    2. A002ACMC02
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A43 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A43-13 (CANH) - A43-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

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


    1. Reconnect the A43 ECM connector.

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

      A002AHIC11
      *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) - F102-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 4 CAN junction connector
      F102-2 (CANH) - F102-12 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM
      F102-3 (CANH) - F102-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly
      F102-4 (CANH) - F102-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      F102-5 (CANH) - F102-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*1
      F102-6 (CANH) - F102-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      F102-7 (CANH) - F102-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)*2
      F102-8 (CANH) - F102-18 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher 4WD ECU assembly*3
      F102-10 (CANH) - F102-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)

      • *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 branch line) C
      NG (Central gateway ECU (network gateway ECU) branch line) D
      NG (ECM main line) E

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 13 Click here

    D

    CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)) Click here

    E

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (ECM - NO. 3 CAN JUNCTION CONNECTOR)

    B

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


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

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

      A002AHIC09
      *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) - F103-11 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 3 CAN junction connector
      F103-2 (CANH) - F103-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Skid control ECU (brake actuator assembly)
      F103-4 (CANH) - F103-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      F103-5 (CANH) - F103-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      F103-8 (CANH) - F103-18 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor branch line) C
      NG (Combination meter assembly main line) D

    A

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    B

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

    C

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

    D

    REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 4 CAN JUNCTION CONNECTOR)

  12. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


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

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

    3. A002C0MC36
      *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) - F127-17 (CA4L) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    NG

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

  13. 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. A002BTZC08
      *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
      F127-18 (CA4H) - F127-17 (CA4L) 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 CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR