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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 493 (HVAC System - Automatic) >> Diagnostic Information and Procedures >> DTC P2518 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
  2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 1 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage.
  4. Verify the scan tool Low Pressure Switch parameter is Open.
    • If not the specified value, test the signal circuit terminal 3 for a short to voltage.
  5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool Low Pressure Switch parameter is Open.
    • If not the specified value, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  6. If all circuits test normal, test or replace the A/C refrigerant pressure sensor.
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