CAN COMMUNICATION SYSTEM(w/ Toyota Safety Sense) Check Bus 2 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 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

Symptom Trouble Area
No resistance exists between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) 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

  • ECM

  • Combination meter assembly

  • Center airbag sensor assembly

  • Skid control ECU (brake actuator assembly)

  • Main body ECU (multiplex network body ECU)

  • Power steering ECU assembly

  • Certification ECU (smart key ECU assembly)*1

  • Steering angle sensor (spiral cable sub-assembly)

  • Air conditioning amplifier assembly*2

  • Engine stop and start ECU*3

  • Pre-crash safety city sensor

  • No. 1 junction connector

  • No. 2 junction connector

WIRING DIAGRAM

A0049LDE03
A0046PUE03

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. 2 JUNCTION CONNECTOR)


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

    2. Disconnect the No. 2 junction connector.

    3. A0047U7E02
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to No. 2 Junction Connector)
      *b to Steering Angle Sensor (Spiral Cable Sub-assembly)
      *c to Certification ECU (Smart Key ECU Assembly) (w/ Entry and Start System)
      *d to Center Airbag Sensor Assembly
      *e to Power Steering ECU Assembly
      *f to Combination Meter Assembly
      *g to Air Conditioning Amplifier Assembly (w/ Air Conditioning System or PTC Heater)
      *h to No. 1 Junction Connector
      *i to 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 Connected to
      F83-1 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Steering angle sensor (Spiral cable sub-assembly)
      F83-12 (CANL) - F4-16 (BAT)
      F83-3 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Certification ECU (Smart key ECU assembly)*1
      F83-14 (CANL) - F4-16 (BAT)
      F83-4 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Center airbag sensor assembly
      F83-15 (CANL) - F4-16 (BAT)
      F83-6 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Power steering ECU assembly
      F83-17 (CANL) - F4-16 (BAT)
      F83-7 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Combination meter assembly
      F83-18 (CANL) - F4-16 (BAT)
      F83-8 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Air conditioning amplifier assembly*2
      F83-19 (CANL) - F4-16 (BAT)
      F83-10 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 1 junction connector
      F83-21 (CANL) - F4-16 (BAT)
      F83-2 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Central gateway ECU (network gateway ECU)
      F83-13 (CANL) - F4-16 (BAT)

      • *1: w/ Entry and Start System

      • *2: w/ Air Conditioning System or PTC Heater

      Result
      Result Proceed to
      OK A
      NG (No. 1 junction connector main line) B
      NG (ECU or sensor bus line) C
      NG (Central gateway ECU (network gateway ECU) branch line) D

    A

    REPLACE NO. 2 JUNCTION CONNECTOR

    C

    CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU, SENSOR) Click here

    D

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

    B

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


    1. Disconnect the No. 1 junction connector.

    2. A0049U1E02
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to No. 1 Junction Connector)
      *b to Main Body ECU (Multiplex Network Body ECU)
      *c to No. 2 Junction Connector
      *d to Engine Stop and Start ECU (w/ Stop and Start System)
      *e to Pre-crash Safety City Sensor

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      F136-1 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Main body ECU (Multiplex network body ECU)
      F136-12 (CANL) - F4-16 (BAT)
      F136-4 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher No. 2 junction connector
      F136-15 (CANL) - F4-16 (BAT)
      F136-3 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Engine stop and start ECU*1
      F136-14 (CANL) - F4-16 (BAT)
      F136-2 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Lane recognition camera sensor
      F136-13 (CANL) - F4-16 (BAT)

      • *1: w/ Stop and Start System

      Result
      Result Proceed to
      OK A
      NG (No. 2 junction connector main line) B
      NG (ECU or sensor bus line) C

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE (NO. 1 JUNCTION CONNECTOR - NO. 2 JUNCTION CONNECTOR)

    C

    CHECK FOR SHORT TO +B IN CAN BUS LINE (ECU, SENSOR) Click here

    A

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


    1. Disconnect the No. 1 junction connector.

    2. A0049Q4E02
      Text in Illustration
      *1 DLC3
      *a

      Front view of wire harness connector

      (to No. 1 Junction Connector)
      *b to ECM
      *c to Skid Control ECU (Brake Actuator Assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A110-9 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher ECM
      A110-20 (CANL) - F4-16 (BAT)
      A110-10 (CANH) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher Skid control ECU (Brake actuator assembly)
      A110-21 (CANL) - F4-16 (BAT)
      Result
      Result Proceed to
      OK A
      NG (ECU or sensor bus line) B

    A

    REPLACE NO. 1 JUNCTION CONNECTOR

    B

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


    1. Reconnect all wire harness connectors (No. 1 junction connector and No. 2 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. A0048RNE03
      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
      F135-18 (CA4H) - F4-16 (BAT) Cable disconnected from negative (-) battery terminal 6 kΩ or higher
      F135-17 (CA4L) - 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