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Home >> Infiniti >> 2017 >> QX30 Base >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> LAN System (Can) >> DTC/Circuit Diagnosis >> Powertrain Can Communication >> Diagnosis Procedure

Diagnosis Procedure

  1. ERROR ECU CONFIRMATION

    Confirm whether there is error in one ECU or plural ECU on CAN diagnosis function with CONSULT.

    Is error in one ECU or plural ECU?

    One ECU 

    GO TO STEP 2  .

    Plural ECU 

    GO TO STEP 3  .

  2. CHECK ECU CIRCUIT

    Check a circuit for applicable ECU. Refer to following.

    Unit name Circuit Reference
    AWD control unit Circuit between the CAN potential distributor electrical connector (Powertrain) and the AWD control unit DIAGNOSIS PROCEDURE 
    ECM Circuit between the CAN potential distributor electrical connector (Powertrain) and the ECM DIAGNOSIS PROCEDURE 
    Electric shift control unit Circuit between the CAN potential distributor electrical connector (Powertrain) and the electric shift control unit DIAGNOSIS PROCEDURE 
    Fuel pump control module Circuit between the CAN potential distributor electrical connector (Powertrain) and the fuel pump control module DIAGNOSIS PROCEDURE 
    TCM Circuit between the CAN potential distributor electrical connector (Powertrain) and the TCM DIAGNOSIS PROCEDURE 

    Is the inspection result normal?

    YES 

    GO TO STEP 3  .

    NO 

    Repair or replace applicable parts.

  3. CHECK CAN CIRCUIT VOLTAGE

    1. Turn ignition switch ON.
    2. Check voltage between CAN potential distributor electrical connector (powertrain) harness connector each terminals.
      Terminals Voltage
      (Approx.)
      + -
      CAN potential distributor electrical connector (powertrain)
      Terminal Terminal
      CAN-H Ground 2.5 - 2.7 V
      CAN-L Ground 2.1 - 2.4 V
      CAN-H CAN-L 0.2 - 0.4 V

    Is the inspection result normal?

    YES 

    Check intermittent incident. Refer to INTERMITTENT INCIDENT .

    NO 

    GO TO STEP 4  .

  4. CHECK HARNESS CONNECTOR CONDITION

    1. Turn ignition switch OFF.
    2. Check each harness connector connected to CAN potential distributor electrical connector for proper connection, locking, loose contact, damage, contamination and corrosion.

    Is the inspection result normal?

    YES 

    GO TO STEP 5  .

    NO 

    Securely connects or repair the harness connectors.

  5. CHECK CAN POTENTIAL DISTRIBUTOR ELECTRICAL CONNECTOR

    1. Turn ignition switch OFF.
    2. Disconnect all of harness connector from CAN potential distributor electrical connector (Powertrain).
    3. Check CAN potential distributor electrical connector (Powertrain). Refer to COMPONENT INSPECTION [CAN POTENTIAL DISTRIBUTOR ELECTRICAL CONNECTOR (POWERTRAIN)] .

    Is the inspection result normal?

    YES 

    GO TO STEP 6  .

    NO 

    Replace CAN potential distributor electrical connector (Powertrain).

  6. POSSIBLE CAUSE CONFIRMATION

    1. Turn ignition switch ON.
    2. Check the voltage between CAN potential distributor electrical connector (Powertrain) terminals (CAN-H and CAN-L).
      NOTE:

      [Recommend] Check CAN potential distributor electrical connector (Powertrain) terminals that harness connector is not connected.

    3. Disconnect each harness connector from CAN potential distributor electrical connector (Powertrain) one by one.
    4. Check the voltage change when the harness connector just disconnected.
      Terminals Condition Voltage
      (Approx.)
      + -
      CAN potential distributor electrical connector (powertrain)
      Terminal Terminal
      CAN-H CAN-L When the harness connector just disconnected. No change

    Is the inspection result normal?

    YES 

    Check intermittent incident. Refer to INTERMITTENT INCIDENT .

    NO 

    GO TO STEP 7  .

  7. CHECK SHORT CIRCUIT

    Check the possible cause circuit for short to battery or ground.

    Unit name Circuit Reference
    AWD control unit Circuit between the CAN potential distributor electrical connector (Powertrain) and the AWD control unit DIAGNOSIS PROCEDURE 
    ECM Circuit between the CAN potential distributor electrical connector (Powertrain) and the ECM DIAGNOSIS PROCEDURE 
    Electric shift control unit Circuit between the CAN potential distributor electrical connector (Powertrain) and the electric shift control unit DIAGNOSIS PROCEDURE 
    Fuel pump control module Circuit between the CAN potential distributor electrical connector (Powertrain) and the fuel pump control module DIAGNOSIS PROCEDURE 
    TCM Circuit between the CAN potential distributor electrical connector (Powertrain) and the TCM DIAGNOSIS PROCEDURE 

    Is the inspection result normal?

    YES 

    Replace applicable ECU.

    NO 

    Repair or replace harness.

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