I wired my Ford Windstar with brake lights that come on with my motorhome lights, and running lights. This was to a plug on my tow dolly, and also the tow dolly had lights powered by the motorhome.
I put a diode on each light on the rear, for turn/brake signals, and connected the 'white' wire to ground the van to the motorhome lights, brown wire to the running lights in the front of the van, that turned on all the lights when towing.
I moved the diodes over to my new 2007 Ford Edge, and installed a 4 wheels down towing kit on that car, it is SO much easier to tow 4 wheels down, and no need to park the dolly someplace at each campground. Also the 4 wheel down towing only puts about 30 pounds of weight on the tow hitch, while the tow dolly with the 2,200 pound front axle on it might have put around 200 - 250 pounds on the hitch.
I did not leave the keys in the van while it was on the tow dolly. I did have to remember all 7 steps - especially after leaving a campground, hearing a s****ing sound behind me, and discovered the latch to keep the 'tilt' in the up position forgotten! That was on the third time I towed with the dolly, and I never forgot anything for the next 2 years that I full timed with the dolly.
Good luck,
Fred.
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