Diagnosing a 12-volt deep cycle component starts with an understanding of what appliances operate on 12-Volt vs. 120-volt, and how the system is wired. For years, the negative cable of the house battery was connected to the chassis or undercarriage foundation which was used as a ground source for appliances and components throughout the RV. A positive wire ran from the distribution center and the component was “grounded” to the nearest conductive metal such as the sidewall or roof frame. Loose connections, weak or broken welds, and road vibration created “gremlins” when troubleshooting. Learn a quick and easy way to bypass all these gremlins to verify proper grounding as well as other troubleshooting tips.