Purchased a 95 Trooper,runs great, but no audio! Components installed,Clarion VS715 DVD/CD player, Pyle PLVIN70 monitor, and Virtual Reality Labs VR3 200watt, 2 channel amp. All of these have power, (the time, date, display on the monitor doesn't light, but the monitor works) but with no head unit....there's no volume control, thus no sound! What can I do?