CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU) Check CAN Bus Line for Short to +B (LHD Models)

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of the DLC3.

Symptom Trouble Area
No resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of the DLC3.

  • Short in CAN main bus line

  • Short in CAN branch line

  • Combination meter assembly

  • Certification ECU (smart key ECU assembly)*1

  • Steering sensor (spiral cable with sensor sub-assembly)*2

  • Radio and display receiver assembly*3

  • Airbag sensor assembly

  • Power steering ECU assembly

  • Air conditioning amplifier assembly*4

  • Clearance warning ECU assembly*5

  • Engine stop and start ECU*6

  • Brake actuator assembly

  • Main body ECU (multiplex network body ECU)

  • Headlight swivel ECU assembly*7

  • ECM

  • Driving support ECU assembly*8

  • Pre-crash safety city sensor*9

  • No. 1 CAN junction connector*10

  • No. 3 CAN junction connector

  • No. 4 CAN junction connector*11

WIRING DIAGRAM

A01LW0TE07
A01LYYZE01
A01LWI7E01
A01M3F2E01

CAUTION / NOTICE / HINT

Note


  • 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

  • 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

  • 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 31 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) 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

Tech Tips


  • Operating the ignition switch, any other switches or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE


  1. CHECK VEHICLE TYPE


    1. Check vehicle type.

      Result
      Result Proceed to
      for Sedan A
      except Sedan B

    B

    CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 3 CAN JUNCTION CONNECTOR) Click here

    A

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


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

    2. Disconnect the E57 No. 3 CAN junction connector.

      A01LW9EC13
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to Airbag Sensor Assembly
      *c

      to Air Conditioning Amplifier Assembly

      (w/ Air Conditioning System)

      		 *d

      to Radio and Display Receiver Assembly

      (for Radio and Display Type)
      *e to Combination Meter Assembly *f to No. 1 CAN Junction Connector
      *g

      to Certification ECU (Smart Key ECU Assembly)

      (w/ Entry and Start System)

      		 *h

      to Clearance Warning ECU Assembly

      (w/ Simple Intelligent Parking Assist System)
      *i

      to Engine Stop and Start ECU

      (w/ Stop and Start System)

      		 *j

      to Driving Support ECU Assembly

      (for 1ND-TV with Driving Support ECU)
      *k to Power Steering ECU Assembly *l

      to Steering Sensor (Spiral Cable with Sensor Sub-assembly)

      (w/ VSC)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      E57-1 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Airbag sensor assembly
      E57-12 (CANL) - E11-16 (BAT)
      E57-2 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Air conditioning amplifier assembly*1
      E57-13 (CANL) - E11-16 (BAT)
      E57-3 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Radio and display receiver assembly*2
      E57-14 (CANL) - E11-16 (BAT)
      E57-4 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Combination meter assembly
      E57-15 (CANL) - E11-16 (BAT)
      E57-5 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 1 CAN junction connector
      E57-16 (CANL) - E11-16 (BAT)
      E57-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Certification ECU (smart key ECU assembly)*3
      E57-17 (CANL) - E11-16 (BAT)
      E57-7 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Clearance warning ECU assembly*4
      E57-18 (CANL) - E11-16 (BAT)
      E57-8 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Engine stop and start ECU*5
      E57-19 (CANL) - E11-16 (BAT)
      E57-8 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Driving support ECU assembly*6
      E57-19 (CANL) - E11-16 (BAT)
      E57-9 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Power steering ECU assembly
      E57-20 (CANL) - E11-16 (BAT)
      E57-10 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Steering sensor (spiral cable with sensor sub-assembly)*7
      E57-21 (CANL) - E11-16 (BAT)

      • *1: w/ Air Conditioning System

      • *2: for Radio and Display Type

      • *3: w/ Entry and Start System

      • *4: w/ Simple Intelligent Parking Assist System

      • *5: w/ Stop and Start System

      • *6: for 1ND-TV with Driving Support ECU

      • *7: w/ VSC

      Result
      Result Proceed to
      OK A
      NG (No. 1 CAN junction connector main line) B
      NG (ECU or sensor bus line) C

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 6 Click here

    B

  3. CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 1 CAN JUNCTION CONNECTOR)


    1. Disconnect the A32 No. 1 CAN junction connector.

      A01LW9EC14
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)

      		 *b to No. 3 CAN Junction Connector
      *c to DLC3 *d to Main Body ECU (Multiplex Network Body ECU)
      *e to Brake Actuator Assembly *f to ECM

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A32-1 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 3 CAN junction connector
      A32-12 (CANL) - E11-16 (BAT)
      A32-2 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher DLC3
      A32-13 (CANL) - E11-16 (BAT)
      A32-3 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Main body ECU (multiplex network body ECU)
      A32-14 (CANL) - E11-16 (BAT)
      A32-5 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Brake actuator assembly
      A32-16 (CANL) - E11-16 (BAT)
      A32-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher ECM
      A32-17 (CANL) - E11-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor bus line) C
      NG (DLC3 branch line) D

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

    C

    GO TO STEP 6 Click here

    D

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

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


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

    2. Disconnect the E57 No. 3 CAN junction connector.

      A01LW9EC15
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b

      to Air Conditioning Amplifier Assembly

      (w/ Automatic Air Conditioning System)
      *c

      to Radio and Display Receiver Assembly

      (for Radio and Display Type)

      		 *d to Combination Meter Assembly
      *e to No. 4 CAN Junction Connector *f

      to Certification ECU (Smart Key ECU Assembly)

      (w/ Entry and Start System)
      *g to Airbag Sensor Assembly *h

      to Engine Stop and Start ECU

      (w/ Stop and Start System)
      *i to Power Steering ECU Assembly *j to Steering Sensor (Spiral Cable with Sensor Sub-assembly)
      *k

      to Pre-crash Safety City Sensor

      (w/ Toyota Safety Sense)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      E57-2 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Air conditioning amplifier assembly*1
      E57-13 (CANL) - E11-16 (BAT)
      E57-3 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Radio and display receiver assembly*2
      E57-14 (CANL) - E11-16 (BAT)
      E57-4 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Combination meter assembly
      E57-15 (CANL) - E11-16 (BAT)
      E57-5 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 4 CAN junction connector
      E57-16 (CANL) - E11-16 (BAT)
      E57-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Certification ECU (smart key ECU assembly)*3
      E57-17 (CANL) - E11-16 (BAT)
      E57-7 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Airbag sensor assembly
      E57-18 (CANL) - E11-16 (BAT)
      E57-8 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Engine stop and start ECU*4
      E57-19 (CANL) - E11-16 (BAT)
      E57-9 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Power steering ECU assembly
      E57-20 (CANL) - E11-16 (BAT)
      E57-10 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Steering sensor (spiral cable with sensor sub-assembly)
      E57-21 (CANL) - E11-16 (BAT)
      E57-11 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Pre-crash safety city sensor*5
      E57-22 (CANL) - E11-16 (BAT)

      • *1: w/ Automatic Air Conditioning System

      • *2: for Radio and Display Type

      • *3: w/ Entry and Start System

      • *4: w/ Stop and Start System

      • *5: w/ Toyota Safety Sense

      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 6 Click here

    B

  5. CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 4 CAN JUNCTION CONNECTOR)


    1. Disconnect the A174 No. 4 CAN junction connector.

      A01LW9EC21
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to No. 3 CAN Junction Connector
      *c to DLC3 *d to Main Body ECU (Multiplex Network Body ECU)
      *e

      to Headlight Swivel ECU Assembly

      (w/ Automatic Headlight Beam Level Control System)

      		 *f to Brake Actuator Assembly
      *g to ECM *h

      to Clearance Warning ECU Assembly

      (w/ Simple Intelligent Parking Assist System)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A174-1 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 3 CAN junction connector
      A174-12 (CANL) - E11-16 (BAT)
      A174-2 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher DLC3
      A174-13 (CANL) - E11-16 (BAT)
      A174-3 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Main body ECU (multiplex network body ECU)
      A174-14 (CANL) - E11-16 (BAT)
      A174-4 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Headlight swivel ECU assembly*1
      A174-15 (CANL) - E11-16 (BAT)
      A174-5 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Brake actuator assembly
      A174-16 (CANL) - E11-16 (BAT)
      A174-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher ECM
      A174-17 (CANL) - E11-16 (BAT)
      A174-7 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Clearance warning ECU assembly*2
      A174-18 (CANL) - E11-16 (BAT)

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

      • *2: w/ Simple Intelligent Parking Assist System

      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor bus line) C
      NG (DLC3 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

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    C

  6. CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU, SENSOR)


    1. Reconnect all wire harness connectors.

    2. Disconnect the ECU or sensor connected to the CAN bus line that is shorted to +B.

      Tech Tips

      If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus lines. To determine the ECU or sensor that is connected to the shorted bus line, refer to Terminals of ECU.

      Click here

    3. A01M0A9C17
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E11-6 (CANH) - E11-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      E11-14 (CANL) - E11-16 (BAT)

      Tech Tips

      If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.

      Result
      Result
      OK
      NG

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR