1. Disconnect the negative cable from the car battery. If you're using a DVOM, place it in the lowest "OHMS" range.
2. Connect one lead of a self-powered test light or DVOM to one end of the part of the circuit you want to test.
3. Connect the other lead to the other end.
4. If the self-powered test light glows, there is continuity. If you're using a DVOM, a low reading or no reading (zero), means good continuity.