I have one remote wire run from the back of my HU to the sub box where its split into two....When the car is not running, but on accessory, the HU is on, my Nine.4 is on (speakers on), but my Nine.1 is off (subs off)
Your sub amp wont turn on if theres not enough juice. If your battery is sitting under 12 volts, it may not sence enough power and stay off, like a protection feature. Like M.S. Use a volt meter and test battery, amps, and rem wire voltages at accesory position, and when running.