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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 463 (Engine Cooling System) >> Diagnostic Information and Procedures >> Coolant Heater Inoperative >> Circuit/System Testing

Circuit/System Testing

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NOTE:

The power supply cord will test open due to an internal thermal switch if the ambient temperature is warmer than -10°C (14°F). The thermal switch is designed to close when the ambient temperature is below -18°C (0°F).

  1. Test the engine coolant heater for an open or short to ground.
    • If open or shorted, replace the heater.
  2. If the heater tests normal, replace the coolant heater power cord.