Where is Brake Output Circuit on 2002 Ford F-150 to Connect 7-Way to

Question:

I have a 2002 Ford f150. I have a curt brake controller with the optional lead to connect it to my factory wired plug next to the diagnostic port. My question is where can I connect the blue wire from my 7 pin plug? I have looked under the truck where my 4 flat plug wires are but I cant find a blue wire. It disappears under the dash and is impossible to trace. If it has the factory plug where does the blue wire connect? I have power to my controller and the red light comes on when I depress the brake pedal and also when I use the manual switch on the controller. Just need to know where to connect my blue wire. Thanks

asked by: Donnie M