Have an 06 titan & purchased a Reese brakeman controller & harness & relays from dealer. The Brake controller has 4 wires, the harness has 5. I don't know what to do with the red/blue wire from the harness. The function is marked as ILL. Here's how I've connected the wires (harness-controller).
Red-Black
Black-White
Brn/White-Blue
Red/Green-Red
Red/Blue-???
Sorry it's not more technical. Any suggestions?