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Home >> Infiniti >> 2024 >> QX55 Essential >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can System (DTC/Circuit Diagnosis) >> Circuit Diagnosis >> Main Line Between HVAC And EPS/DAST 3 Circuit >> Diagnosis Procedure

Diagnosis Procedure

  1. CHECK CONNECTOR 
    1. Turn the ignition switch OFF.
    2. Disconnect the battery cable from the negative terminal.
    3. Check the following terminals and connectors for damage, bend and loose connection (connector side and harness side).
      • Harness connector M31
      • Harness connector E152

    Is the inspection result normal?

    >>

    GO TO 2.

    >>

    Repair the terminal and connector.

  2. CHECK HARNESS CONTINUITY (OPEN CIRCUIT) 
    1. Disconnect the following harness connectors.
      • A/C auto amp.
      • Harness connectors M31 and E152
    2. Check the continuity between the A/C auto amp. harness connector and the harness connector.
      • With rear heated seats
        A/C auto amp. harness connector Harness connector Continuity
        Connector No. Terminal No. Connector No. Terminal No.
        M54 1 M31 56J Existed
        21 66J Existed
      • Without rear heated seats
        A/C auto amp. harness connector Harness connector Continuity
        Connector No. Terminal No. Connector No. Terminal No.
        M65 1 M31 56J Existed
        17 66J Existed

    Is the inspection result normal?

    >>

    GO TO 3.

    >>

    Repair the main line between the A/C auto amp. and the harness connector M31.

  3. CHECK HARNESS CONTINUITY (OPEN CIRCUIT) 
    1. Disconnect the connector of EPS control unit (without Direct Adaptive Steering system) or steering force control module (with Direct Adaptive Steering system).
    2. Check the continuity between the harness connectors.
      • Without Direct Adaptive Steering system
        Harness connector EPS control unit harness connector Continuity
        Connector No. Terminal No. Connector No. Terminal No.
        E152 56J E11 8 Existed
        66J 7 Existed
      • With Direct Adaptive Steering system
        Harness connector Steering force control module harness connector Continuity
        Connector No. Terminal No. Connector No. Terminal No.
        E152 56J E141 14 Existed
        66J 15 Existed

    Is the inspection result normal?

    >>

    Check CAN system type decision again.

    >>

    • Without Direct Adaptive Steering system: Error was detected in the main line between the A/C auto amp. and the EPS control unit
    • With Direct Adaptive Steering system: Error was detected in the main line between the A/C auto amp. and the steering force control module

    >>

    • Without Direct Adaptive Steering system: Repair the main line between the harness connector E152 and EPS control unit
    • With Direct Adaptive Steering system: Repair the main line between the harness connector E152 and steering force control module
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