Lights hack -- Polarity?

[Atsushi]

I've never done it, but I think it's interesting.


https://letscampsmore.com/running-lights-hack/


Here is my question. When you do this trick, do you think the polarity is unchanged from the normal ways these lights are powered?


Why do I want to know? Well, I'm wondering to check the polarity of cables (say for example, cables feeding license plate light) with this method without hitching to a TV.



I know I can/should experiment, but I'm lazy.

[GMFL]

I built a little box with a 7pin female plug that is jumped out with a wire between the battery hot and running lights. It also has a switch that allows me to turn them on and off. It works great.

[rmkrum]

Personally, I’d deeply dislike anybody out camping in the boondocks and deliberately turning on their running lights at night while parked in a site within my view.

I want to see the stars and scenery, not excess running lights, strings of lights, LED strings, whatever.

For test purposes, an adapter box is a darn good idea. A 7-way receptacle in an aluminum box would be rather handy. One more idea for my rapidly growing list of projects, sigh.

[Johnco]

I built one with a two way switch. One circuit is constant on, the other circuit routes through a flasher. It's a back up if I have to leave the trailer roadside at night without the tow vehicle.

[Paprika]

"When you do this trick, do you think the polarity is unchanged from the normal ways these lights are powered?"

I don't see jumpering those two pins could reverse polarity. And if you have LED running lights on your 2016 FC, they would not operate if polarity were reversed...so if you do it and they light up, you have your answer.

[OTRA15]

Originally Posted by rmkrum

Personally, I’d deeply dislike anybody out camping in the boondocks and deliberately turning on their running lights at night while parked in a site within my view.
. . .

I guess flashing lights would be OK?

Originally Posted by Johnco

I built one with a two way switch. One circuit is constant on, the other circuit routes through a flasher.
. . .

[Johnco]

More than OK if you're stuck on the side of the road. You have to give the impaired drivers something to aim for...

[rmkrum]

Flashing lights would get a very loud visit from DW to that person’s campsite. I would be deeply concerned for the miscreant’s personal safety at that point...

And yeah, it’s well known that impaired drivers use flashing lights to define their aim point center—and they usually hit it squarely.

[GMFL]

Originally Posted by Johnco

I built one with a two way switch. One circuit is constant on, the other circuit routes through a flasher. It's a back up if I have to leave the trailer roadside at night without the tow vehicle.

That’s the same thing I did. Flasher is nice if you had to drop the trailer for some reason.

[GMFL]

Originally Posted by Paprika

"When you do this trick, do you think the polarity is unchanged from the normal ways these lights are powered?"

I don't see jumpering those two pins could reverse polarity. And if you have LED running lights on your 2016 FC, they would not operate if polarity were reversed...so if you do it and they light up, you have your answer.

Polarity is unchanged. All you are doing is providing a 12v+ Connection to the positive wire of the running lights. Same thing your TV does through the 7 pin cable when your running lights are on. The only difference is you are using the trailers 12 volt system to power the running lights through a jumper.

[SeeMore]

There is no need to build a flasher. There are many variations that plug directly into the 7-way available on the net. Search for "two-pin 12 volt signal flasher". I stash mine in the glove box for that unforeseen roadside emergency.

Here is an example that works for newer trailers with LED markers:
https://www.ebay.com/itm/2-Pin-12V-E...e/153282229941

The older filament style bulbs use solutions like this one:
https://www.ebay.com/itm/2-PIN-Prong...D/223314822795