I just got a hitch for my truck. I got the 4-wire harness and connected it to the factory wires. The trouble is when I have the lights on and hit the brakes my dash lights dim, this also happens when I use the right turn signal.

I noticed on the wiring harness box it states that for trucks with different lights for brakes and turn signals an adapter is needed. What does this thing do, have anyone else put one of these on? What is it?

All of these questions will probably be moot come tomorrow because I am going to try to pick one up tomorrow where I got the hitch. I still want to know what this thing does. My guess is just a few diodes to block the current.

Thanks guys!!