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Home >> Infiniti >> 2024 >> QX55 Essential >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can System (DTC/Circuit Diagnosis) >> Circuit Diagnosis >> Drivetrain Can Communication >> Diagnosis Procedure

Diagnosis Procedure

  1. CHECK CAN DIAGNOSIS 

    Check the CAN diagnosis results from CONSULT to see that the vehicle CAN communication 1 circuit has no malfunction.

    Is the vehicle CAN communication 1 circuit normal?

    >>

    GO TO 2.

    >>

    Check and repair vehicle CAN communication 1 circuit.

  2. CONNECTOR INSPECTION 
    1. Turn the ignition switch OFF.
    2. Disconnect the battery cable from the negative terminal.
    3. Disconnect all the unit connectors on drivetrain CAN communication circuit.
    4. Check terminals and connectors for damage, bend and loose connection.

    Is the inspection result normal?

    >>

    GO TO 3.

    >>

    Repair the terminal and connector.

  3. CHECK HARNESS CONTINUITY (OPEN CIRCUIT) 

    Check the continuity between the ECM harness connector and the electric intake valve timing control module harness connector.

    ECM harness connector Electric intake valve timing control module harness connector Continuity
    Connector No. Terminal No. Connector No. Terminal No.
    E16 148 F91 3 Existed
    147 1 Existed

    Is the inspection result normal?

    >>

    GO TO 4.

    >>

    Check the harness and repair the root cause.

  4. CHECK HARNESS CONTINUITY (SHORT CIRCUIT) 

    Check the continuity between the ECM harness connector terminals.

    ECM harness connector Continuity
    Connector No. Terminal No.
    E16 148 147 Not existed

    Is the inspection result normal?

    >>

    GO TO 5.

    >>

    Check the harness and repair the root cause.

  5. CHECK HARNESS CONTINUITY (SHORT CIRCUIT) 

    Check the continuity between the ECM harness connector and the ground.

    ECM harness connector Ground Continuity
    Connector No. Terminal No.
    E16 148 Not existed
    147 Not existed

    Is the inspection result normal?

    >>

    GO TO 6.

    >>

    Check the harness and repair the root cause.

  6. CHECK TERMINATION CIRCUIT 
    1. Remove the ECM and the electric intake valve timing control module.
    2. Check the resistance between the ECM terminals.
      ECM Resistance (Ω)
      Terminal No.
      148 147 Approx. 108 - 132
    3. Check the resistance between the electric intake valve timing control module terminals.
      Electric intake valve timing control module Resistance (Ω)
      Terminal No.
      3 1 Approx. 108 - 132

    Is the measurement value within the specification?

    >>

    GO TO 7.

    >>

    Replace the ECM and/or the electric intake valve timing control module.

  7. CHECK SYMPTOM 

    Connect all the connectors. Check if the symptoms described in the "Symptom (Results from interview with customer)" are reproduced.

    Inspection result

    Reproduced>>

    GO TO 8.

    >>

    Start the diagnosis again. Follow the trouble diagnosis procedure when past error is detected.

  8. CHECK UNIT REPRODUCTION 

    Perform the reproduction test as per the following procedure for each unit.

    1. Turn the ignition switch OFF.
    2. Disconnect the battery cable from the negative terminal.
    3. Disconnect one of the unit connectors of drivetrain CAN communication circuit.
      NOTE: SYMBOL ECM and electric intake valve timing control module have a termination circuit. Check other units first.
    4. Connect the battery cable to the negative terminal. Check if the symptoms described in the "Symptom (Results from interview with customer)" are reproduced.
      NOTE: SYMBOL Although unit-related error symptoms occur, do not confuse them with other symptoms.

    Inspection result

    Reproduced>>

    Connect the connector. Check other units as per the above procedure.

    >>

    Replace the unit whose connector was disconnected.

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