CAN COMMUNICATION SYSTEM(w/o Central Gateway ECU) Check CAN Bus Lines for Short Circuit (LHD Models)

DESCRIPTION

There may be a short circuit between the V bus main lines and/or CAN branch lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 6 (CANH) and 14 (CANL) of DLC3 is below 54 Ω.

  • Short in CAN main bus line

  • Short in CAN branch line

  • Combination meter assembly

  • Certification ECU (Smart key ECU assembly)*1

  • Steering sensor (Spiral cable with sensor sub-assembly)*2

  • Radio and display receiver assembly*3

  • Airbag sensor assembly

  • Power steering ECU assembly

  • Air conditioning amplifier assembly*4

  • Clearance warning ECU assembly*5

  • Engine stop and start ECU*6

  • Brake actuator assembly

  • Main body ECU (Multiplex network body ECU)

  • AFS ECU (Headlight swivel ECU assembly)*7

  • ECM

  • No. 1 CAN junction connector

  • No. 3 CAN junction connector

WIRING DIAGRAM

A012MNRE03
A012G98E03

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 (-) 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 (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) 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 and wait at least 31 seconds, and then drive the vehicle at a speed of 20 km/h (12 mph) or more.

  • After the repair, perform the CAN 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.

PROCEDURE


  1. CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY - NO. 3 CAN JUNCTION CONNECTOR)


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

    2. A012L92C22
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the E46 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E46-32 (CANH) - E46-31 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK A
      NG (for 1NR-FE, 1ZR-FAE, 1ZR-FE or 2ZR-FE engine) B
      NG (for 1ND-TV engine) C
      NG (for 1AD-FTV engine) D

    A

    REPLACE COMBINATION METER ASSEMBLY for Sedan: Click here for Hatchback, Wagon: Click here

    C

    CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 1 CAN JUNCTION CONNECTOR) Click here

    D

    CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 1 CAN JUNCTION CONNECTOR) Click here

    B

  2. CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the E46 combination meter assembly connector.

    2. A012IM5C17
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A50 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A50-13 (CANH) - A50-26 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result Proceed to
      OK (for 1NR-FE engine) A
      OK (for 1ZR-FAE engine) B
      OK (for 1ZR-FE engine) C
      OK (for 2ZR-FE engine) D
      NG E

    A

    REPLACE ECM Click here

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here

    D

    REPLACE ECM Click here

    E

    GO TO STEP 5 Click here

  3. CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the E46 combination meter assembly connector.

    2. A012L27C03
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A101 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A101-3 (CANH) - A101-4 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    GO TO STEP 5 Click here

  4. CHECK FOR SHORT IN CAN BUS LINES (ECM - NO. 1 CAN JUNCTION CONNECTOR)


    1. Reconnect the E46 combination meter assembly connector.

    2. A012LVTC02
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the A118 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A118-7 (CANH) - A118-6 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω
      Result
      Result
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  5. CHECK FOR SHORT IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR)


    1. Reconnect the A50, A101 or A118 ECM connector.

    2. A012FWNC25
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)
      *b to Airbag Sensor Assembly
      *c to Air Conditioning Amplifier Assembly*1
      *d to Radio and Display Receiver Assembly*2
      *e to Combination Meter Assembly
      *f to No. 1 CAN Junction Connector
      *g to Certification ECU (Smart Key ECU Assembly)*3
      *h to Clearance Warning ECU Assembly*4
      *i to Engine Stop and Start ECU*5
      *j to Power Steering ECU Assembly
      *k to Steering Sensor (Spiral Cable with Sensor Sub-assembly)*6

      Disconnect the E57 No. 3 CAN junction connector.


      • *1: w/ Air Conditioning System

      • *2: for Radio and Display Type

      • *3: w/ Entry and Start System

      • *4: w/ Simple Intelligent Parking Assist System

      • *5: w/ Stop and Start System

      • *6: w/ VSC

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      E57-1 (CANH) - E57-12 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Airbag sensor assembly
      E57-2 (CANH) - E57-13 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Air conditioning amplifier assembly*1
      E57-3 (CANH) - E57-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Radio and display receiver assembly*2
      E57-4 (CANH) - E57-15 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω Combination meter assembly
      E57-5 (CANH) - E57-16 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω No. 1 CAN junction connector
      E57-6 (CANH) - E57-17 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Certification ECU (Smart key ECU assembly)*3
      E57-7 (CANH) - E57-18 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Clearance warning ECU assembly*4
      E57-8 (CANH) - E57-19 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Engine stop and start ECU*5
      E57-9 (CANH) - E57-20 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Power steering ECU assembly
      E57-10 (CANH) - E57-21 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Steering sensor (Spiral cable with sensor sub-assembly)*6

      • *1: w/ Air Conditioning System

      • *2: for Radio and Display Type

      • *3: w/ Entry and Start System

      • *4: w/ Simple Intelligent Parking Assist System

      • *5: w/ Stop and Start System

      • *6: w/ VSC

      Result
      Result Proceed to
      OK A
      NG (No. 1 CAN junction connector main line) B
      NG (ECU or sensor branch line) C
      NG (Combination meter assembly main line) D

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    GO TO STEP 7 Click here

    D

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 3 CAN JUNCTION CONNECTOR)

    B

  6. CHECK FOR SHORT IN CAN BUS LINES (NO. 1 CAN JUNCTION CONNECTOR)


    1. A012FWNC23
      *a

      Front view of wire harness connector

      (to No. 1 CAN Junction Connector)
      *b to No. 3 CAN Junction Connector
      *c to DLC3
      *d to Main Body ECU (Multiplex Network Body ECU)
      *e to AFS ECU (Headlight Swivel ECU Assembly)*1
      *f to Brake Actuator Assembly
      *g to ECM

      Disconnect the A32 No. 1 CAN junction connector.

      *1: w/ AFS (Adaptive Front-lighting System)

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      A32-1 (CANH) - A32-12 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher No. 3 CAN junction connector
      A32-2 (CANH) - A32-13 (CANL) Cable disconnected from negative (-) battery terminal 1 MΩ or higher DLC3
      A32-3 (CANH) - A32-14 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Main body ECU (Multiplex network body ECU)
      A32-4 (CANH) - A32-15 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher AFS ECU (Headlight swivel ECU assembly)*1
      A32-5 (CANH) - A32-16 (CANL) Cable disconnected from negative (-) battery terminal 200 Ω or higher Brake actuator assembly
      A32-6 (CANH) - A32-17 (CANL) Cable disconnected from negative (-) battery terminal 108 to 132 Ω ECM

      *1: w/ AFS (Adaptive Front-lighting System)

      Result
      Result Proceed to
      OK A
      NG (No. 3 CAN junction connector main line) B
      NG (ECU or sensor branch line) C
      NG (DLC3 branch line) D
      NG (ECM main line) E

    A

    REPLACE NO. 1 CAN JUNCTION CONNECTOR

    B

    REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 1 CAN JUNCTION CONNECTOR - NO. 3 CAN JUNCTION CONNECTOR)

    D

    REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

    E

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

    C

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


    1. Reconnect all wire harness connectors (No. 1 CAN junction connector and No. 3 CAN junction connector).

    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. A012I5TC19
      *1 DLC3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E11-6 (CANH) - E11-14 (CANL) Cable disconnected from negative (-) 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).

      Result
      Result
      OK
      NG

    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR