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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 118 (Engine Controls And Fuel - 3.6L (LF4 LGX) - DTC P0685 LGX To DTC P3436 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Cylinder Deactivation (Active Fuel Management) System Diagnosis (LGX) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2016 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, all vehicle systems OFF, remove the fuse from the underhood fuse block that is suppling voltage to the valve lifter oil solenoids. It may take up to 2 min for all vehicle systems to power down.
  2. Connect a DMM between the output terminal of the fuse and the K20 Engine Control Module housing.
  3. Ignition ON, command Cylinder Deactivation System ON with the scan tool.
  4. Verify the resistance of each solenoid is between 11-18 Ω.
    • If not between 11-18 Ω for both cylinder deactivation solenoids 
    1. Ignition OFF.
    2. Test for less than 2 Ω on the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, refer to Component Testing.
    • If not between 11-18 Ω for one cylinder deactivation solenoid 
    1. Ignition OFF.
    2. Test for less than 2 Ω on the appropriate control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω
    3. Test for 11-18 Ω between the ignition circuit and the appropriate control circuit at the Q83 Valve Lifter Oil Solenoid Valve.
      • If not within the specified value, test or replace the Q83 Valve Lifter Oil Solenoid Valve.
      • If within the specified value, test or replace the K20 Engine Control Module.
    • If between 11-18 Ω 
    5. WARNING:

    Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

  5. Operate the vehicle within the conditions of the customer's concern while monitoring the Cylinder Deactivation Inhibit parameters.
  6. Verify all Cylinder Deactivation Inhibit parameters display NO.
    • If any parameter displays YES 

      Refer to the appropriate vehicle system to determine the cause for cylinder deactivation inhibit.

    • If none of the parameters display YES 
  7. Test or replace the Q83 Valve Lifter Oil Solenoid Valve.
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