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Home >> Cadillac >> 2010 >> Escalade EXT >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System & Fuel System - 5.3L, 6.0L, 6.2L - DTC P1255 To DTC P3449 >> DTC P3400 >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, remove the valve lifter oil manifold assembly ignition fuse from the underhood fuse block.
    2. NOTE: Probe each terminal at the underhood fuse block with a test lamp connected to ground to determine what terminal to connect the DMM. The test lamp should not illuminate on the circuit that needs to be tested.
  2. Connect a DMM between the ignition circuit fuse terminal going to the valve lifter oil manifold assembly and the ECM housing.
  3. Ignition ON, command each Cylinder 1, 4, 6, and 7 Deactivation solenoid ON and OFF with the scan tool. Verify the resistance of each solenoid is between 11-18 Ω with the solenoid commanded ON.
    • If greater than the specified range for all cylinder deactivation solenoids, test the ignition circuit for an open/high resistance.
    • If greater than the specified range for one or more but not all cylinder deactivation solenoids, test both the control circuit and ignition circuit for an open/high resistance or an open/high resistance in the cylinder deactivation solenoid. If the circuits and solenoid test normal replace the ECM.
  4. If all circuits and components test normal, refer to Cylinder Deactivation (Active Fuel Management) Valve Lifter Oil Manifold Diagnosis and Testing for further mechanical diagnosis of valve lifter oil manifold assembly.
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