I know there have been a ton of threads about factory sub issues. But none of them seem to have the solution I need. I have 2007 expedition limited with factory sub, ( audiophile system I think? ) I recently installed an aftermarket sub and amp. I used the 5 wires for the factory sub amp. Using a LOC connected to the 2 factory sub signal wires. This was all working fine at first. I had to take out the sub and amp for a couple of days, and when I put it back in suddenly, no sound. None of the wiring was messed with. I am 100% getting power. My amp turns on/ 12v on factory amp power confirmed. But there is no audio signal whatsoever on the factory signal wires. I even tried connecting a speaker I had laying around directly to it, nothing. Also have tried 3 different amps both with LOC and with high level input. And have tried 2 different LOC. all just to confirm there is no audio on the signal wires. I've searched high and low for any solution and nothing. I've also tried pulling the battery and draining power from the truck to hopefully reset anything. this is driving me nuts. Is there something inside the factory head unit that could turn off the sub maybe ?