Originally Posted by txsailorboy
Regarding the magnetic lights.....how does the plug (for the magnetic lights) and the plug (for the dolly lights) mate to the RV's outlet...i.e. is there a "Y" connection involved?
Generally there is no provision on a dolly to add lights for the vehicle itself. What we did was purchase a trailer socket with a bracket like this:
Hopkins Endurance 7-Way Trailer Connector Socket - Vehicle End - Ergonomic Design Hopkins Wiring HM48480
and a plug like this:
Hopkins Endurance Metal Trailer Connector - 7-Pole RV Style - Trailer End Hopkins Wiring HM48510
I mounted the socket on the tongue of the dolly and tapped into the dolly wiring harness for the tail lights, brake lights, and directional lights. You don't really need a 7 way socket and plug. We just used them because they came with a bracket that could be permanently mounted on the dolly. All you really need is a 4 way socket because you'll only need wires for lights not brakes or battery charging.
The 7 way socket is more robust and weather protected, and still inexpensive. We had about $25.00 in wires, socket with bracket, and plug (to replace the 4 way plug on the magnetic lights). In total the cost was about $50.00 for everything including the lights.
We originally used a cheaper plug, but found it wasn't water tight. We got water in the plug and it caused all kinds of weird problems. The water in the plug caused the backup light terminal to short to the brake light terminal. Sometimes the backup camera on the motorhome would come on when we stepped on the brake, or turned on a directional signal. It was getting an errant signal from the water in the plug. When we changed out the original plug for one that was water tight the problems went away.