CAN COMMUNICATION SYSTEM(w/ Toyota Safety Sense) Open in Bus 3 Main Bus Line

DESCRIPTION

There may be an open circuit in one of the bus 3 main lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is 70 Ω or higher.

Symptom Trouble Area
Resistance between terminals 6 (CA3H) and 21 (CA3L) of central gateway ECU (network gateway ECU) is 70 Ω or higher.

  • CAN main bus line or connector

  • Central gateway ECU (network gateway ECU)

  • CAN junction connector LH

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

A004G3AE07

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 as normal 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 (CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))


    1. Remove the central gateway ECU (network gateway ECU) Click here.

    2. A004FUBE01
      Text in Illustration
      *a

      Component without 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
      F89-6 (CA3H) - F89-21 (CA3L) Always 108 to 132 Ω
      F89-19 (CAYH) - F89-20 (CAYL) Always 108 to 132 Ω

    NG

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) Click here

    OK

  2. CHECK FOR OPEN IN CAN BUS LINES (CAN J/C LH)


    1. Reinstall the central gateway ECU (network gateway ECU) Click here.

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

    3. A004E85E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to CAN Junction Connector LH)
      *b to Central Gateway ECU (Network Gateway ECU) (CA3H and CA3L Terminal)
      *c to Central Gateway ECU (Network Gateway ECU) (CAYH and CAYL Terminal)

      Disconnect the CAN junction connector LH.

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F90-7 (CANH) - F90-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU) (CA3H and CA3L terminal)
      F90-6 (CANH) - F90-17 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Central gateway ECU (network gateway ECU) (CAYH and CAYL terminal)

    OK

    REPLACE CAN JUNCTION CONNECTOR LH

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN J/C LH - CENTRAL GATEWAY ECU)