CAN COMMUNICATION SYSTEM(w/ Toyota Safety Sense) Check Bus 3 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the bus 3 main lines and/or CAN branch lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CA3H) and 21 (CA3L) of central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus line

  • Short in CAN branch line

  • Central gateway ECU (network gateway ECU)

  • Radio and display receiver assembly*1

  • CAN junction connector LH

WIRING DIAGRAM

A004FOKE02

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 SHORT 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 SHORT 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. Disconnect the CAN junction connector LH.

    4. A004EJQE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to CAN Junction Connector LH)
      *b Central Gateway ECU (Network Gateway ECU) (CA3H and CA3L Terminal)
      *c Central Gateway ECU (Network Gateway ECU) (CAYH and CAYL Terminal)
      *d to Radio and Display Receiver Assembly (w/ Display)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F90-5 (CANH) - F90-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Radio and display receiver assembly*1
      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)
      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)

      • *1: w/ Display

      Result
      Result Proceed to
      OK A
      NG (ECU or sensor branch line) B
      NG (Central gateway ECU (network gateway ECU) main line) C

    A

    REPLACE CAN JUNCTION CONNECTOR LH

    C

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

    B

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


    1. Reconnect all wire harness connectors (CAN junction connector LH).

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the short circuited branch line is connected Click here.

    3. A004G5PE02
      Text in Illustration
      *a

      Component with 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) Cable disconnected from negative (-) auxiliary 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