How do I hook a 3 pin connector to a 4 pin?

Since the camper connector has "DC" embossed on the jacket, there is no reason to believe it has any pinout relationship with a standard 4-way trailer connector. I'd suggest to check continuity with the pins on the connector and frame ground, a running light fixture, any backup lights on the camper, any taillight fixtures, and a wire leading to the battery compartment (should have one of those three colors).

If you want connectivity to the truck, I'd suggest to buy a 4-way "Y" splitter (fairly typical and easy to source) and make a custom pigtail to connect to the camper. You can buy both genders of individual pins to make the pigtail (might even get lucky and find the 3 way connector to modify).

Good luck on your wiring, that's a sweet rig.

MEXICOWANDERER wrote:
Might be useful to note that tail lights and running lights in this case, are the very same connection.

That's true in pretty much every RV wiring case.

Might be useful to note that tail lights and running lights in this case, are the very same connection.

I would convert truck and trailer wiring to conventional 4-wire. It would pay off in the long run. But, that's just me.

Yup, that 3-pin is not standard for trailering. Odds are you would've blown a fuse or two had you tried to plug that into a 4-pin trailer connector.

Get your 12V jumper box, and a couple of nails to use as probe pins, and figure out which wire does what. As stated above you probably have running lights, 12V "house" power, and ground.

What you can then do is wire up a custom adapter using a 7-pin Pollack style connector, with a 4-pin for the trailer and a 3-pin for the camper. The 3-pin can be made from a 4-pin by hacksawing off the extra pin.

You will probably need to install the "Stud #1" fuse in the fuse panel under the hood of your truck, in order to get 12V power to the trailer plug.

wnjj wrote:
Ok so your camper has no tail lights. You probably have ground, running lights and +12v for interior lights. You'll have to wire up something custom from the 7-way on the truck or just put a 7-way on the camper.

Be sure to figure out what each does before hooking them up.

x3

With new information, I go along with wnjj.
You still should test to be sure.

Ok so your camper has no tail lights. You probably have ground, running lights and +12v for interior lights. You'll have to wire up something custom from the 7-way on the truck or just put a 7-way on the camper.

Be sure to figure out what each does before hooking them up.

Thanks for all the info guys! I wasn't too clear about my set up, I have the new to me(ntm} camper on my truck and a utility/camping gear hauler trailer that the truck tows. The trailer is connected by the typical 4 pin and all its lights work great. My initial idea was to get a splitter and/or adapter that goes to both the trailer and camper, but was not sure how to do it because I cant find a 4 to 3 pin adaptor.

All the info you've posted is great and I'll start testing what is what and when I figure it out I'll post the results, probably really basic but this is all new to me.

thanks again, Brian

camper ready to return home after purchase a few weeks ago, small but since I have a 1/2 ton truck its perfect, beats the hell out of the shell I previously used. Pic is a bit blurry and distorted, cell phone camera



gear hauler trailer, made from old utility bed and truck frame its mounted on

Depends on the lights

On the 4 pin the "odd" one is ground
Then the one next to it is tail light/running lights

Right and left turn/stop are the remaining two (not sure the order
I do not I am thinking that on your trailer either they use the hitch as the ground in which caSe you going to have to adapt.. OR.. they left something off (tail lights perhaps).. In any case I think you are in for work

You will need to identify each wire as to what it feeds. And as I said. not sure if the "odd" one will be tail light or ground.