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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1538 (Immobilizer System) >> Diagnostic Information and Procedures >> DTC P254F >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the hood ajar switch.
  2. Ignition OFF, test for less than 10 ohms between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, test for 10.0-12.5 volts between the signal circuit terminal B and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the SGCM.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SGCM.
  4. Ignition ON, test for 10.0-12.5 volts between the signal circuit terminal C and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the SGCM.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SGCM.
  5. Ignition OFF, disconnect the harness connector at the hood ajar switch.
  6. Ignition ON, observe the scan tool SGCM Hood Position parameter. With the hood open, the Hood Position parameter should read Open. With the hood closed, the Hood Position parameter should read Closed.
    • If the parameter does not change between the specified values, test or replace the hood ajar switch.
  7. Observe the scan tool ECM Hood Position parameter. With the hood open, the Hood Position parameter should read Open. With the hood closed, the Hood Position parameter should read Closed.
    • If the parameter does not change between the specified values, replace the ECM.
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