Trailer wiring questions

[99EB5.0]

On my 99 eb I've got the plugs under the tail lights on both sides. I can't find a wiring harness to run trailer lights. Anyone have part numbers or suggestions? Thanks in advance

 

[RomeovilleIL]

Drivers side tail light plug is for the trailer lights. Hopkins 40915 is OEM fit plug in. Gives you a 4-flat. Usually around $15 at most parts stores.

 

[99EB5.0]

What's the plug for on the passenger side?

 

[RomeovilleIL]

I was told once it was used for testing purposes during assembly in the plants, but honestly dont know. It didnt have any live current when I put a tester on the pins a few years ago.

 

[99EB5.0]

Thanks for all the help. I found the wiring harness at Oreillys