CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU) Check CAN Bus Lines for Short Circuit (LHD Models)

DESCRIPTION

There may be a short circuit between the V bus main lines and/or CAN branch lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

  • Short in CAN main bus lines

  • Short in CAN branch lines

  • Combination meter assembly

  • Power steering ECU with motor assembly

  • Main body ECU (multiplex network body ECU)

  • Steering sensor

  • Airbag sensor assembly

  • ECM

  • Brake actuator assembly (skid control ECU)

  • Air conditioning amplifier assembly

  • Certification ECU (smart key ECU assembly)

  • Radio receiver assembly*1*2

  • Clearance warning ECU assembly

  • Telematics transceiver*3

  • Engine stop and start ECU*4

  • Headlight leveling ECU (headlight swivel ECU assembly)

  • CAN junction connector LH1

  • CAN junction connector RH1

WIRING DIAGRAM

A01W0ENE03
A01W1LRE04

CAUTION / NOTICE / HINT

Note


  • Before measuring the resistance of the CAN bus, turn the engine 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 engine 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 engine switch on (IG), wait at least 60 seconds, drive the vehicle at a speed of 20 km/h (12 mph) or more at least 5 minutes and then allow the cruise control system to operate for 3.58 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 Service Bulletin.

Tech Tips


  • Operating the engine 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 FOR SHORT IN CAN BUS LINES (CAN J/C LH1)


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

    2. Disconnect the H213 CAN junction connector LH1.

      A01VZMYE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to CAN Junction Connector LH1)

      		 *b to Headlight Leveling ECU (Headlight Swivel ECU Assembly)
      *c

      to Engine Stop and Start ECU

      (for 6AR-FSE)

      		 *d to Steering Sensor
      *e to Main Body ECU (Multiplex Network Body ECU) *f to DLC3
      *g to Airbag Sensor Assembly *h to Combination Meter Assembly
      *i to CAN Junction Connector RH1 *j to Power Steering ECU with Motor Assembly

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      H213-1 (CANH) - H213-11 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Headlight leveling ECU (headlight swivel ECU assembly)
      H213-3 (CANH) - H213-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Engine stop and start ECU*
      H213-4 (CANH) - H213-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor
      H213-5 (CANH) - H213-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (multiplex network body ECU)
      H213-6 (CANH) - H213-16 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher DLC3
      H213-7 (CANH) - H213-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      H213-8 (CANH) - H213-18 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      H213-9 (CANH) - H213-19 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω CAN junction connector RH1
      H213-10 (CANH) - H213-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU with motor assembly

      • *: for 6AR-FSE

      Result
      Result Proceed to
      OK A
      NG (CAN junction connector RH1 main lines) B
      NG (ECU or sensor branch lines) C
      NG (DLC3 branch lines) D
      NG (Combination meter assembly main lines) E

    A

    REPLACE CAN JUNCTION CONNECTOR LH1

    C

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

    D

    REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO DLC3

    E

    CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY) Click here

    B

  2. CHECK FOR SHORT IN CAN BUS LINES (CAN J/C LH1 - CAN J/C RH1)


    1. Reconnect the H213 CAN junction connector LH1.

    2. A01W3BYE05
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction Connector RH1)
      *b to CAN Junction Connector LH1

      Disconnect the H122 CAN main bus line connector.

      Note


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

      • Reconnect the connector to its original position.

    3. A01W3BWE02
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (CAN J/C LH1 - CAN J/C RH1)

    OK

  3. CHECK FOR SHORT IN CAN BUS LINES (CAN J/C RH1)


    1. Reconnect the H122 CAN main bus line connector.

    2. A01W3BWE02
      Text in Illustration
      *1 DLC3

      Connect the probes of an electrical tester to terminals 6 (CANH) and 14 (CANL) of the DLC3.

    3. While observing the resistance value shown on the electrical tester, disconnect connectors (H123, H126, H127, H128, H132 and H200) from the CAN junction connector RH1 one by one until the resistance becomes normal (between 54 and 69 Ω).

      A01W5HNE19
      Text in Illustration
      *a

      Component without harness connected

      (CAN Junction Connector RH1)

      		 - -
      Wiring Color
      CAN Junction Connector RH1 Side Code Color (CANH Side) Color (CANL Side)
      Telematics transceiver*1 H200 BE W
      Clearance warning ECU assembly H132 P W
      Certification ECU (Smart key ECU assembly) H127 V W
      Brake actuator assembly (skid control ECU) H126 Y W
      Radio receiver assembly*2*3 H128 L W
      Air conditioning amplifier assembly H123 G W
      CAN main bus line (bus line connecting CAN junction connector LH1 and CAN junction connector RH1) H122 R W
      ECM H125 B W

      • *1: w/ Telematics Transceiver

      • *2: for Navigation Receiver Type

      • *3: for Radio and Display Type

      Note

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

      Result
      Result Proceed to
      The resistance is still below 54 Ω when all the specified connectors are disconnected. (There are no shorts between a pair of branch lines.) A
      The resistance becomes normal (between 54 and 69 Ω) when a connector is disconnected. (There is a short between one or more pairs of branch lines.) B

    4. When there is a short in one or more of the branch lines:


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the short-circuited bus line). Check that the resistance shown on the electrical tester is normal (between 54 and 69 Ω) to confirm that there is a short 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.


    B

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

    A

  4. CHECK FOR SHORT IN CAN BUS LINES (ECM MAIN BUS LINE)


    1. A01W4AYE03
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to CAN Junction Connector RH1)
      *b to ECM

      Disconnect the H125 ECM main bus line connector.

      Note


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

      • Reconnect the connector to its original position.

    2. A01W3BWE02
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      The resistance is still below 54 Ω when the ECM connector is disconnected. (There are no shorts in the ECM or between its main bus lines.) A
      The resistance becomes normal (between 108 to 132 Ω) when the ECM connector is disconnected. (There is a short in the ECM or between its main bus lines.) B

    A

    REPLACE CAN JUNCTION CONNECTOR RH1

    B

  5. CHECK FOR SHORT IN CAN BUS LINES (ECM)


    1. Reconnect the H125 ECM main bus line connector.

    2. Disconnect the A22, A64 or A75 ECM connector.

    3. A01W3BWE02
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK (for 2GR-FE) A
      OK (for 2AR-FE) B
      OK (for 6AR-FSE) C
      NG D

      Tech Tips

      If the resistance becomes normal (between 108 to 132 Ω) when the connector is disconnected, there may be a short in the ECM.


    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here

    D

    REPAIR OR REPLACE CAN MAIN BUS LINES (ECM MAIN LINES)

  6. CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)


    1. Reconnect the connector for the short-circuited branch line to the CAN junction connector (the connector that caused the bus line resistance to become normal (between 54 and 69 Ω) 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 short-circuited branch line is connected Click here.

    3. A01W3BWE02
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-14 (CANL) 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.


    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 (COMBINATION METER ASSEMBLY)


    1. Reconnect the H213 CAN junction connector LH1.

    2. Disconnect the H14 combination meter assembly connector.

    3. A01W3BWE02
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-14 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω

      Tech Tips

      If the resistance becomes normal (between 108 to 132 Ω) when the connector is disconnected, there may be a short in the combination meter assembly.


    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (COMBINATION METER ASSEMBLY MAIN LINES)