The problem is probably that your current is not correct. You can have perfectly good voltage on a circuit, but if you have a loose connection or broken strands on a wire, then the current might not be getting through to power the component. This is where the load light comes into play.

A load light is nothing more than a bulb or bulbs connected in parallel, with 2 wires connected for hooking up into the circuit. Usually small bulbs are used because they are easy to handle and take less to power up. A store bought load light, shown below, will also do the trick. They usually run from $3 to $10.

                                      load light

Load lights are connected at a bare wire end, or at any open point in a circuit. You can also stick the load light wire or needle end directly into a connector's positive power contact. The other wire should be connected to your parts ground or chassis. If the load light illuminates, then you should have correct current in your circuit, if it does not illuminate, then you have a loose connection, broken wire strands, or an open somewhere in the circuit.

Also, if your load light illuminates very dim, check another similar circuit if possible to compare brightness. You may just have a weak power source on the dim circuit. Using a load light is relatively easy to do, and you might just save some time and money by not replacing a working part.   

                                        See more how-to articles