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Home >> Infiniti >> 2024 >> QX55 Essential >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can System (DTC/Circuit Diagnosis) >> Circuit Diagnosis >> EPS/DAST 3 Branch Line 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 (unit side and connector side).
      • EPS control unit (without Direct Adaptive Steering system)
      • Steering force control module (with Direct Adaptive Steering system)

    Is the inspection result normal?

    >>

    GO TO 2.

    >>

    Repair the terminal and connector.

  2. CHECK HARNESS FOR 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 resistance between the EPS control unit harness connector terminals (without Direct Adaptive Steering system) or the steering force control module harness connector terminals (with Direct Adaptive Steering system).
      • Without Direct Adaptive Steering system
        EPS control unit harness connector Resistance (Ω)
        Connector No. Terminal No.
        E11 8 7 Approx. 54 - 66
      • With Direct Adaptive Steering system
        Steering force control module harness connector Resistance (Ω)
        Connector No. Terminal No.
        E141 14 15 Approx. 54 - 66

    Is the measurement value within the specification?

    >>

    GO TO 3.

    >>

    Repair the EPS control unit branch line (without Direct Adaptive Steering system) or the steering force control module branch line (with Direct Adaptive Steering system).

  3. CHECK POWER SUPPLY AND GROUND CIRCUIT 

    Check the power supply and the ground circuit of the EPS control unit (without Direct Adaptive Steering system) or the steering force control module (with Direct Adaptive Steering system). Refer to the following.

    Is the inspection result normal?

    >>

    Replace the EPS control unit (without Direct Adaptive Steering system) or the steering force control module (with Direct Adaptive Steering system). Refer to the following.

    >>

    Error was detected in the EPS control unit branch line (without Direct Adaptive Steering system) or the steering force control module branch line (with Direct Adaptive Steering system).

    >>

    Repair the power supply and the ground circuit.