there isn't really a lot of pics and such on towbars/flat towing so i thought i would just post a few of the wiring i did to make my tj's tail lights and rear clearance lights come on through the tow rig's power.
here is the 4-way plug stashed under the grille. it is out of the way and has a weather cap. bonus...
the patch line from the truck to the above plug. the 7-way to 4-way is something i had already. with the flat wire it stores compactly.
here is a pic of the diode packs going in. four in total. in truth i could have used just three but i wanted to have a spare onboard and swapping to a 3-way get-up would be simple enough.
completed diode install. on the right is the fuse and relay for my reverse lights that currently are burned out.... need to buy some more gooder bulbs for those.
incase you don't know why the diodes have to go inline..... they act as a non return valve or a check valve for electrical current.
the diode packs have two inlets and one outlet. the truck and jeep harness go into the two side and out of the one side comes 12v current for lights. when the jeep is under its own power the diodes are invisible and the jeep works normally. same for the tow rig.
anyways, it all kind of works like automatic switches.
one other thing. some will ground the towed rig through the ball and coupler. the 4 wire has enough to run a ground all the way back to the lights. the coupler grounding method doesnt really optimize your lighting efforts.
pictures of the tow bar to come if interested.
guess i should say this kit can be had for less than $50.00.
i did not like the piggyback taps or the blade plugs so i used water tight plugs solder and heat shrink. it is not 100% waterproof but the area where everything is stashed is pretty clean after a dozen years of assorted fun...