Trailer Plug Problem

[Paul shaw]

I have a 2011 Rt It originally came with a brp trailer The problem I was given a tailer which has the 4 prong plug the RT has a 9 prong plug I have been trying to find the female plug that. The brp. It has the harness that you get are for connecting the BRP trailer to you car it has the male end.

[4 MARIE]

Is English your "second" language? I only ask because your last sentence is confusing.
Do the search function on here and pull up the 9 pin wiring diagram.
Relate that to the fourwire (square or flat?) connector on trailer,
then go to etrailer.com for an appropriate adapter. OR...
Since trailer was given to you, why not splurge and get the harness and isolator you need for your RT, and change that 9 pin thingy, out?