Trailer Wiring

Have a 2002 town and country van. I bought a plug in for trailer lights where you separate an existing plug and plug in this trailer wiring What I need to know is where is the existing plug located:confused: I know I will get an answer and thanks for that up front You guys and gals are awesome!
Bob

depends on the wiring model,but the one I used you had to remove the rear tail lights unplug the factory wire plug,and then plug in the trailer plug and behind that was the factory plug. so it looked like this... tail light+ trailer plug+ factory plug. might be the same for yours