I just plugged in a factory subwoofer in my ’07 Lariat S Crew but I have no sound coming from it. I used the factory cable under the back seat. I also pulled out the factory navigation/head unit and verified that all three plugs were plugged into the back (all pins have wires coming from them).
I called the guy at the parts counter and he said that I might need to have the head unit reprogrammed. Does this make any sense? Why would it not just be plug & play?

Thanks.

 

I have never done what you are doing, but, might there be an empty fuse location for a factory sub?