I discovered my trailer lights were not working at all so I replaced my trailer lights with new ones. I hooked my trailer lights back up to the truck and only the left side trailer lights would work. I replaced the old adapter with a new one and still got the same results. I went to the local parts stores and nobody had a clue what the part was called or what it was. After doing some research online I found it and ordered the 19 dollar part. Now I've just got to get my lazy butt under the truck and take the old one off and put the new one on.