CAN COMMUNICATION SYSTEM(w/o Toyota Safety Sense) Open in CAN Main Bus Line (LHD Models)

DESCRIPTION

There may be an open circuit in one of the V bus main lines and/or a DLC3 branch line when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is 70 Ω or higher.

Symptom Trouble Area
Resistance between terminals 6 (CANH) and 14 (CANL) of DLC3 is 70 Ω or higher.

  • DLC3 branch line or connector

  • CAN main bus line or connector

  • ECM

  • Combination meter assembly

  • CAN junction connector LH

  • CAN junction connector RH

This malfunction is not related to the lines of a CAN main bus branch or to ECUs or sensors connected a CAN main bus branch.

WIRING DIAGRAM

A01UYIOE04

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, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary 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 (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary 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 (IG), turn the cruise control system on using the cruise control main switch (ON/OFF switch), wait at least 60 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more.

  • After the repair, perform Communication 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 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 wiring harnesses, and to make future maintenance easier.

PROCEDURE


  1. CHECK FOR OPEN IN CAN BUS LINES (DLC3 BRANCH LINE)


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

    2. A01UZGPE01
      Text in Illustration
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F3-6 (CANH) - F3-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

      Note

      When the measured value is 133 Ω or higher and a CAN communication system DTC is output, there may be a fault besides disconnection of the DLC3 branch line. For that reason, troubleshooting should be performed again from How to Proceed with Troubleshooting after repairing the trouble area Click here.


    NG

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    OK

  2. CHECK FOR OPEN IN CAN BUS LINES (COMBINATION METER ASSEMBLY - CAN J/C RH)


    1. A01UZ9LE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F1-32 (CANH) - F1-31 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

  3. CHECK FOR OPEN IN CAN BUS LINES (ECM - CAN J/C LH)


    1. Reconnect the F1 combination meter assembly connector.

    2. A01UY9LE03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A28-13 (CANH) - A28-26 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE ECM Click here

    NG

  4. CHECK FOR OPEN IN CAN BUS LINES (CAN J/C RH)


    1. Reconnect the A28 ECM connector.

    2. A01V270E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to CAN Junction Connector RH)
      *b to Combination Meter Assembly
      *c to CAN Junction Connector LH

      Disconnect the CAN junction connector RH.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F63-7 (CANH) - F63-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Combination meter assembly
      F63-10 (CANH) - F63-21 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω CAN junction connector LH
      Result
      Result Proceed to
      OK A
      NG (Combination meter assembly main line) B
      NG (CAN junction connector LH main line) C

    A

    REPLACE CAN JUNCTION CONNECTOR RH

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN J/C RH - COMBINATION METER ASSEMBLY)

    C

  5. CHECK FOR OPEN IN CAN BUS LINES (CAN J/C LH (INSTRUMENT PANEL WIRE SIDE))


    1. Reconnect the F63 CAN junction connector RH.

    2. A01UYLFE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to CAN Junction Connector LH (Instrument Panel Wire Side))
      *b to CAN Junction Connector RH

      Disconnect the CAN junction connector LH (instrument panel wire side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F62-4 (CANH) - F62-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω CAN junction connector RH

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN J/C LH - CAN J/C RH)

    OK

  6. CHECK FOR OPEN IN CAN BUS LINES (CAN J/C LH (ENGINE ROOM MAIN WIRE SIDE))


    1. Reconnect the F62 CAN junction connector LH (instrument panel wire side).

    2. A01UZODE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to CAN Junction Connector LH (Engine Room Main Wire Side))
      *b to ECM

      Disconnect the CAN junction connector LH (engine room main wire side).

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A34-9 (CANH) - A34-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM

    OK

    REPLACE CAN JUNCTION CONNECTOR LH

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN J/C LH - ECM)