Alright. After much searching, both on this forum, others, and in my vehicle itself, I have come to the conclusion that my truck, an '04 F150, is not equipped with a subwoofer harness. Since I was not able to find the answer by searching through the forums, I was hoping someone out there would be able to tell me if an aftermarket company sells an add-on harness for the factory setup, if anyone knows of a ford factory part number, or if someone has a wiring diagram so I can build my own. Or, if by the grace of God, someone has replaced their oem setup with aftermarket, and has the harness that they would like to sell, please let me know. Thank you all in advance.

 

I have an 04 f150 and mine has the factory subwoofer cable and my truck came without the audiophile or the woofer. So I guess if you're sure its not there but I would make double sure. I found it easier to find on the headunit side, if you find the grey plug on the headunit side taped around the main stereo harness it must come out the other side. If this is the case do what I did: just make up your mind that its under that back seat some where, get mad, and grab that sucker and pull

 

It's almost like you know me. Getting mad and tearing things apart is my MO. Alas, I have searched high and low in the truck to no avail. I checked under the seat and all throughout the dash behind the HU, but found no evidence of the harness. I guess I am just one of the unlucky ones. So it is either wire it up myself (which I would be fine doing, had I a diagram) or find one to plug and play (which I would prefer, to save the trouble and frustration).

 

Here's a link I have found very useful the last couple days doing my stereo system. Just join up and you have access to basic and model specific wiring diagrams.

http://www.the12volt.com/