Diagnosis And Testing - Engine Block Heater Testing
WARNING: This page is about a different car, the 2004 Dodge Grand Caravan, 2004 Dodge Caravan, and 2004 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
If unit does not operate, trouble can be in either the power cord or the heater element. Test power cord for continuity with a 110-volt voltmeter or 110-volt test light; test heater element continuity with an ohmmeter or 12-volt test light.