This should be a plug-in adapter with four relays built into it. As I recall, there is a cover to remove from under the vehicle, right behind the left rear tire.
If you look at the rear lights, I'm pretty sure you're going to find the brake light bulb is not the same as the turn signal bulb. That is where the problem comes in and you can't just splice in the older four-wire trailer harness. Trailers have the more common turn signal and brake functions being done by the same bulb. Splicing in that four-wire harness would short together the vehicle's brake lights to its separate signal lights so they'd all come on when any circuit is energized.
If my memory is wrong and you have a single lamp doing the brake and signal function on the vehicle, Here are the wiring diagram to find wire colors (below)
Check out the diagrams (Below)
Please let us know if you need anything else to get the problem fixed.
Images (Click to enlarge)
Thursday, October 29th, 2015 AT 12:52 PM