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Home >> Subaru >> 2015 >> BRZ Limited, Standard Trans >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can Communication System >> Can Communication System >> Checking CAN Communication Circuit

Checking CAN Communication Circuit

  1. Inspection steps
    CAUTION:
    • Before measuring the resistance of CAN bus, turn the ignition OFF and leave the vehicle as is for at least one minute without operating keys, switches, and doors. Disconnect the battery and wait for another one minute or more.
    • When a connector is not fully connected, it may case CAN communication failure. To avoid such failure, make sure to perform contact pressure test.
    1. Bring in the car
      1. Use the tester to measure the resistance between terminals.

        Resistance

        Inspection terminals Inspection conditions Standard value
        D10-6 - chassis ground Always 10Ω or more
        D10-14 - chassis ground Always 10Ω or more
        Fig 1: Data Link Connector Terminal Identification
        G10215996Courtesy of SUBARU OF AMERICA, INC.

        NG: Check for ground short. (Refer to CHECK FOR SHORT TO GROUND  )

        OK: Go to next step

    2. Checking from data link connector
      1. Use the tester to measure the voltage between terminals.

        Voltage

        Inspection terminals Inspection conditions Standard value
        D10-6 - chassis ground Always Less than 5 V
        D10-14 - chassis ground Always Less than 5 V
        Fig 2: Data Link Connector Terminal Identification
        G10215997Courtesy of SUBARU OF AMERICA, INC.

        NG: Check for short circuit in the battery (Refer to CHECK FOR SHORT TO BATTERY  )

        OK: Go to next step

    3. Checking from data link connector
      1. Use the tester to measure the resistance between terminals.

        Resistance

        Inspection terminals Inspection conditions Standard value
        D10-6 - D10-14 Always 57 to 63 Ω
        Fig 3: Data Link Connector Terminal Identification
        G10215998Courtesy of SUBARU OF AMERICA, INC.

        Criteria

        Result Go to
        OK (57 to 63 Ω) A
        NG (63 Ωor more) B
        NG (less than 57 Ω) C

        A: A sub-line may be open. Perform the inspection for the resistance between the sub-lines relevant to the detected DTC. (Refer to 2. list)

        B: Perform the inspection for the resistance of 63 Ω OR MORE . (Refer to )

        C: Perform the inspection for the resistance of LESS THAN 57 Ω . (Refer to )

  2. List
    Item Contents Note
    Check for short to ground Refer to "CHECK FOR SHORT TO GROUND ". (Refer to ) Shorted to ground in the communication circuit or control module.
    Check for short to battery Refer to "CHECK FOR SHORT TO BATTERY ". (Refer to ) Shorted to battery power supply system in the communication circuit or control module.
    Less than 57 Ω Refer to the inspection for the resistance of LESS THAN 57 Ω . (Refer to ) CAN-H and CAN-L may be shorted on CAN communication circuit, where the resistance is lower than combined resistance of the terminal resistor.
    63Ω or more Refer to the inspection for the resistance of 63 Ω OR MORE . (Refer to ) CAN communication circuit may be open on CAN communication circuit, where the resistance is higher than combined resistance of the terminal resistor.
    Sub-lines 57-63 Ω(Engine control computer system) Refer to the inspection for the SUB-LINES 57-63 Ω (ENGINE CONTROL COMPUTER SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the engine control computer.
    Sub-lines 57-63 Ω(Brake actuator assembly system) Refer to the inspection for the SUB-LINES 57-63 Ω (BRAKE ACTUATOR ASSEMBLY SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the brake actuator assembly.
    Sub-lines 57-63 Ω(Transmission control computer assembly system) Refer to the inspection for the SUB-LINES 57-63 Ω (TRANSMISSION CONTROL COMPUTER ASSEMBLY SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the transmission control computer assembly.
    Sub-lines 57-63 Ω(Body integrated unit system) Refer to the inspection for the SUB-LINES 57-63 Ω(BODY INTEGRATED UNIT SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the body integrated unit.
    Sub-lines 57-63 Ω(Spiral cable sub-assembly system) Refer to the inspection for the SUB-LINES 57-63 Ω(SPIRAL CABLE SUB-ASSEMBLY SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the spiral cable sub-assembly.
    Sub-lines 57-63 Ω(Air conditioner amplifier assembly system) Refer to the inspection for the SUB-LINES 57-63 Ω(A/C CONTROL PANEL SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for A/C.
    Sub-lines 57-63 Ω(Electric power steering computer assembly system) Refer to the inspection for the SUB-LINES 57-63 Ω(ELECTRIC POWER STEERING COMPUTER ASSEMBLY SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the electric power steering.
    Sub-lines 57-63 Ω(Combination meter assembly system) Refer to the inspection for the SUB-LINES 57-63 Ω(COMBINATION METER ASSEMBLY SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the meter.
    Sub-lines 57-63 Ω(Airbag system) Refer to the inspection for the SUB-LINES 57-63 Ω(A/B CM SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the airbag.
    Sub-lines 57-63 Ω(Keyless access system) Refer to the inspection for the SUB-LINES 57-63 Ω(KEYLESS ACCESS SYSTEM) . (Refer to ) The inspection is applied in case of missing or invalid data for the collation ECM (Smart key computer assembly).
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