CAN COMMUNICATION SYSTEM Check CAN Bus Line for Short to GND (LHD Models)

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminals 6 (CANH) and 4 (CG) or 14 (CANL) and 4 (CG) of the DLC3.

Symptom Trouble Area
No resistance exists between terminals 6 (CANH) and 4 (CG) or 14 (CANL) and 4 (CG) of DLC3.

  • Short to ground in CAN main bus line

  • Short to ground in CAN branch line

  • AFS ECU*1

  • ECM

  • Main body ECU (Multiplex network body ECU)

  • Combination meter assembly

  • Brake actuator assembly

  • Steering sensor

  • Clearance warning ECU assembly*2

  • Power steering ECU with motor assembly

  • Airbag sensor assembly

  • Air conditioning amplifier assembly

  • Smart key ECU assembly (Certification ECU)*3

  • Navigation receiver assembly*4

  • Radio and display receiver assembly*5

  • Network gateway ECU*6

  • Inner rear view mirror assembly*7

  • CAN No. 1 junction connector

  • CAN No. 2 junction connector

*1: w/ AFS

*2: w/ Toyota Parking Assist-sensor System

*3: w/ Smart Entry and Start System

*4: for Navigation Receiver Type

*5: for Radio and Display Type

*6: w/ Network Gateway ECU

*7: w/ Automatic High Beam System

WIRING DIAGRAM

B000JGCE06
B000IKRE01
B000JTUE02

INSPECTION PROCEDURE

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, wait at least 31 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 5 minutes. Check that the warning light remains off after turning off following the initial light check.

  • After the repair, perform 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.

  • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines. When the connectors have been disconnected from the CAN junction connector, reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wire harnesses, and to make future maintenance easier.

PROCEDURE


  1. CHECK VEHICLE TYPE


    1. Check vehicle type.

      Result
      Result Proceed to
      except TMMR Made A
      for TMMR Made B

    B

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

    A

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE (DLC3 BRANCH LINE)


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

    2. B000K99E06
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 1 Junction Connector)
      *b to DLC3

      Disconnect the DLC3 branch line connector (I96) from the CAN No. 1 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    OK

  3. CHECK FOR SHORT TO GND IN CAN BUS LINE


    1. Reconnect the DLC3 branch line connector (I96) to the CAN No. 1 junction connector.

    2. B000J27E03
      Text in Illustration
      *1 DLC3

      Disconnect the connectors (I94, I95, I97, I100, I102, I103, I104, I105, I106, I107, I111, I112 and I188) from the CAN No. 1 junction connector and CAN No. 2 junction connector one at a time.

      Tech Tips

      Disconnect the ECU and sensor connectors other than the DLC3 branch lines and CAN main bus lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.

    3. Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 4 (CG), and between terminals 14 (CANL) and 4 (CG) of the DLC3 each time a connector is disconnected.

      B000L9UE02
      Text in Illustration
      *A w/ Toyota Parking Assist-sensor System *B w/ Smart Entry and Start System
      *C for Navigation Receiver Type *D for Radio and Display Type
      *E w/ Network Gateway ECU *F w/ AFS
      *1 Clearance Warning ECU Assembly *2 Air Conditioning Amplifier Assembly
      *3 ECM *4 Brake Actuator Assembly
      *5 Smart Key ECU Assembly (Certification ECU) *6 Navigation Receiver Assembly
      *7 Radio and Display Receiver Assembly *8 Network Gateway ECU
      *9 Combination Meter Assembly *10 Power Steering ECU with Motor Assembly
      *11 DLC3 *12 Airbag Sensor Assembly
      *13 Steering Sensor *14 Main Body ECU (Multiplex Network Body ECU)
      *15 AFS ECU *16 CAN No. 1 Junction Connector
      *17 CAN No. 2 Junction Connector - -
      B000HORE20
      Text in Illustration
      *a

      Component without harness connected

      (CAN No. 1 Junction Connector)

      		 - -
      Wiring Color
      CAN No. 1 Junction Connector Side Code Color (CANH Side) Color (CANL Side)
      AFS ECU* I112 BE W
      Main body ECU (Multiplex network body ECU) I95 P W
      Steering sensor I97 V W
      Airbag sensor assembly I103 Y W
      DLC3 I96 L W
      Power steering ECU with motor assembly I100 G W
      Combination meter assembly I94 R W
      CAN main bus line (bus line connecting CAN No. 1 junction connector and CAN No. 2 junction connector) I93 B W

      *: w/ AFS

      B000NK6E01
      Text in Illustration
      *a

      Component without harness connected

      (CAN No. 2 Junction Connector)

      		 - -
      Wiring Color
      CAN No. 2 Junction Connector Side Code Color (CANH Side) Color (CANL Side)
      CAN main bus line (bus line connecting CAN No. 1 junction connector and CAN No. 2 junction connector) I101 B W
      Air conditioning amplifier assembly I102 V W
      ECM I104 P W
      Smart key ECU assembly (Certification ECU)*1 I106 L W
      Clearance warning ECU assembly*2 I111 BE W
      Network Gateway ECU*3 I188 G W

      • Navigation receiver assembly*4

      • Radio and display receiver assembly*5

      		 I107 R W
      Brake actuator assembly I105 Y W

      *1: w/ Smart Entry and Start System

      *2: w/ Toyota Parking Assist-sensor System

      *3: w/ Network Gateway ECU

      *4: for Navigation Receiver Type

      *5: for Radio and Display Type

      Note

      Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to GND in 2 or more CAN bus lines.

      Result
      Symptom Proceed to
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) is still below 200 Ω when all the specified connectors are disconnected from the CAN junction connector. (There is a short to GND in the CAN main bus lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.) A
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) becomes normal (200 Ω or higher) when a connector is disconnected from the CAN junction connector. (There is a short to GND in one of the areas that relate to the disconnected bus lines.) B

    4. When there is a short to GND in one or more of the bus lines that connect to an ECU or sensor:


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the bus line that is shorted to GND). Check that the resistance shown on the tester is normal (200 Ω or higher) to confirm that there is a short to GND in the one branch line only.

        Tech Tips


        • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

        • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wire harnesses, and to make future maintenance easier.

    5. When there is no short to GND in any of the bus lines that connect to the ECUs and sensors:


      1. With all the specified connectors for ECUs and sensors disconnected, proceed with the inspection of the CAN bus main lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.


    B

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

    A

  4. CHECK CAN NO. 1 JUNCTION CONNECTOR


    1. B000LGXE10
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 1 Junction Connector)
      *b to CAN No. 2 Junction Connector

      Disconnect the CAN main bus line connector (I93) from the CAN No. 1 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    2. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

    OK

  5. CHECK CAN NO. 2 JUNCTION CONNECTOR (CAN NO. 1 J/C - CAN NO. 2 J/C)


    1. Reconnect the CAN main bus line connector (I93) to the CAN No. 1 junction connector.

    2. B000HHSE02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 2 Junction Connector)
      *b to CAN No. 1 Junction Connector

      Disconnect the CAN main bus line connector (I101) from the CAN No. 2 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN BUS MAIN LINE (CAN NO. 1 JUNCTION CONNECTOR - CAN NO. 2 JUNCTION CONNECTOR)

    OK

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

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


    1. Reconnect the connector of the bus line that is shorted to GND to the CAN junction connector (the connector that caused the bus line resistance to change to 200 Ω or higher when it was disconnected).

    2. Disconnect the connector that includes the DLC3 connected CAN lines (such as CANH and CANL) from the ECU or sensor to which the bus line shorted to GND is connected Click here.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

      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.


    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

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


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

    2. Disconnect the I198 CAN No. 1 junction connector.

      B000KJME02
      Text in Illustration
      *1 DLC3 - -
      *a

      Front view of wire harness connector

      (to CAN No. 1 Junction Connector)

      		 *b

      to AFS ECU*1

      (for V Bus)
      *c

      to Combination Meter Assembly

      (for V Bus)

      		 *d

      to Main Body ECU (Multiplex Network Body ECU)

      (for V Bus)
      *e

      to DLC3

      (for V Bus)

      		 *f

      to Steering Sensor

      (for V Bus)
      *g

      to Airbag Sensor Assembly

      (for V Bus)

      		 *h

      to Power Steering ECU with Motor Assembly

      (for V Bus)
      *i

      to Inner Rear View Mirror Assembly*2

      (for V Bus)

      		 *j

      to CAN No. 2 Junction Connector

      (for V Bus)

      *1: w/ AFS

      *2: w/ Automatic High Beam System

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I198-1 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher AFS ECU*1
      I198-11 (CANL) - I39-4 (CG)
      I198-2 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Combination meter assembly
      I198-12 (CANL) - I39-4 (CG)
      I198-3 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (Multiplex network body ECU)
      I198-13 (CANL) - I39-4 (CG)
      I198-4 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher DLC3
      I198-14 (CANL) - I39-4 (CG)
      I198-5 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      I198-15 (CANL) - I39-4 (CG)
      I198-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      I198-16 (CANL) - I39-4 (CG)
      I198-7 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU with motor assembly
      I198-17 (CANL) - I39-4 (CG)
      I198-8 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher Inner rear view mirror assembly*2
      I198-18 (CANL) - I39-4 (CG)
      I198-10 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher CAN No. 2 junction connector
      I198-20 (CANL) - I39-4 (CG)

      *1: w/ AFS

      *2: w/ Automatic High Beam System

      Result
      Result Proceed to
      OK A
      NG (CAN No. 2 junction connector main lines) B
      NG (DLC3 branch line) C
      NG (ECU or sensor bus line) D

    B

    CHECK CAN NO. 2 JUNCTION CONNECTOR (CAN NO. 1 J/C - CAN NO. 2 J/C) Click here

    C

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    D

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

    A

    REPLACE CAN NO. 1 JUNCTION CONNECTOR

  8. CHECK CAN NO. 2 JUNCTION CONNECTOR (CAN NO. 1 J/C - CAN NO. 2 J/C)


    1. Reconnect the I198 CAN No. 1 junction connector.

    2. B000HHSE02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN No. 2 Junction Connector)
      *b to CAN No. 1 Junction Connector

      Disconnect the CAN main bus line connector (I101) from the CAN No. 2 junction connector.

      Note


      • Before disconnecting the connector, make a note of where it is connected.

      • Reconnect the connector to its original position.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

    NG

    REPAIR OR REPLACE CAN BUS MAIN LINE (CAN NO. 1 JUNCTION CONNECTOR - CAN NO. 2 JUNCTION CONNECTOR)

    OK

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


    1. Reconnect the CAN main bus line connector (I101) to CAN No. 2 junction connector.

    2. B000J27E03
      Text in Illustration
      *1 DLC3

      Disconnect the connectors (I102, I104, I105, I106, I107, I111 and I188) from the CAN No. 2 junction connector one at a time.

      Tech Tips

      Disconnect the ECU and sensor connectors other than the CAN main bus lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.

    3. Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 4 (CG), and between terminals 14 (CANL) and 4 (CG) of the DLC3 each time a connector is disconnected.

      B000NK6E02
      Text in Illustration
      *a

      Component without harness connected

      (CAN No. 2 Junction Connector)

      		 - -
      Wiring Color
      CAN No. 2 Junction Connector Side Code Color (CANH Side) Color (CANL Side)
      CAN main bus line (bus line connecting CAN No. 1 junction connector and CAN No. 2 junction connector) I101 B W
      Air conditioning amplifier assembly I102 V W
      ECM I104 P W
      Smart key ECU assembly (Certification ECU)*1 I106 L W
      Clearance warning ECU assembly*2 I111 BE W

      • Navigation receiver assembly*3

      • Radio and display receiver assembly*4

      		 I107 R W
      Network Gateway ECU*5 I188 G W
      Brake actuator assembly I105 Y W

      *1: w/ Smart Entry and Start System

      *2: w/ Toyota Parking Assist-sensor System

      *3: for Navigation Receiver Type

      *4: for Radio and Display Type

      *5: w/ Network Gateway ECU

      Note

      Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to GND in 2 or more CAN bus lines.

      Result
      Symptom Proceed to
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) is still below 200 Ω when all the specified connectors are disconnected from the CAN junction connector. (There is a short to GND in the CAN main bus lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.) A
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) becomes normal (200 Ω or higher) when a connector is disconnected from the CAN junction connector. (There is a short to GND in one of the areas that relate to the disconnected bus lines.) B

    4. When there is a short to GND in one or more of the bus lines that connect to an ECU or sensor:


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the bus line that is shorted to GND). Check that the resistance shown on the tester is normal (200 Ω or higher) to confirm that there is a short to GND in the one branch line only.

        Tech Tips


        • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

        • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wire harnesses, and to make future maintenance easier.

    5. When there is no short to GND in any of the bus lines that connect to the ECUs and sensors:


      1. With all the specified connectors for ECUs and sensors disconnected, proceed with the inspection of the CAN bus main lines between the CAN No. 1 junction connector and CAN No. 2 junction connector.


    B

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

    A

    REPLACE CAN NO. 2 JUNCTION CONNECTOR

  10. CHECK FOR SHORT TO GND IN CAN BUS LINE (ECU, SENSOR)


    1. Reconnect the connector of the bus line that is shorted to GND to the CAN junction connector (the connector that caused the bus line resistance to change to 200 Ω or higher when it was disconnected).

    2. Disconnect the connector that includes the DLC3 connected CAN lines (such as CANH and CANL) from the ECU or sensor to which the bus line shorted to GND is connected Click here.

    3. B000J27E03
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I39-6 (CANH) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher
      I39-14 (CANL) - I39-4 (CG) Cable disconnected from negative (-) battery terminal 200 Ω or higher

      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.


    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BUS LINE OR CONNECTOR

    OK

    REPLACE CORRESPONDING ECU OR SENSOR