Diagnosis And Testing - Engine Block Heater Testing
WARNING: This page is about a different car, the 2017 RAM ProMaster 3500, 2017 RAM ProMaster 2500, and 2017 RAM ProMaster 1500. However, it is still accessible from the selected car via links, so may be relevant.
If unit does not operate, test power cord for continuity with a 110-volt voltmeter or 110-volt test light. Test heater element continuity with an ohmmeter.