CAN COMMUNICATION SYSTEM(w/ Toyota Safety Sense) Check Bus 3 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom Trouble Area
No resistance exists between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 21 (CA3L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

  • Short to +B in CAN main bus line

  • Short to +B in CAN branch line

  • Central gateway ECU (network gateway ECU)

  • Radio and display receiver assembly*1

  • No. 1 junction connector

WIRING DIAGRAM

A004AOUE02

CAUTION / NOTICE / HINT

Note


  • Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.

  • After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not in operation.

  • Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors. If doors need to be opened in order to check connectors, open the doors and leave them open.

Tech Tips

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

PROCEDURE


  1. CHECK FOR SHORT TO +B IN CAN BUS LINE (NO. 1 JUNCTION CONNECTOR)


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

    2. Disconnect the No. 1 junction connector.

    3. A004A53E02
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to No. 1 Junction Connector)
      *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
      F136-5 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Radio and display receiver assembly*1
      F136-16 (CANL) - F4-16 (BAT)
      F136-6 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Central gateway ECU (network gateway ECU) (CAYH and CAYL terminal)
      F136-17 (CANL) - F4-16 (BAT)
      F136-7 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Central gateway ECU (network gateway ECU) (CA3H and CA3L terminal)
      F136-18 (CANL) - F4-16 (BAT)

      • *1: w/ Display

      Result
      Result Proceed to
      OK A
      NG (ECU or sensor bus line) B

    A

    REPLACE NO. 1 JUNCTION CONNECTOR

    B

  2. CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU, SENSOR)


    1. Reconnect all wire harness connectors (No. 1 junction connector).

    2. Disconnect the ECU or sensor connected to the CAN bus line that is shorted to +B.

      Tech Tips

      If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus lines. To determine the ECU or sensor that is connected to the shorted bus line, refer to the terminals of ECU tables Click here.

    3. A0047KSE02
      Text in Illustration
      *1 DLC3
      *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
      F135-6 (CA3H) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      F135-21 (CA3L) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher

      Tech Tips

      If the resistance changes to 6 kΩ or higher 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 BUS LINE OR CONNECTOR