The Mach radios from Navigators, Expeditions and Explorers around 2001 use a subwoofer amp and the bass signal from the speakers is sent to that amp with a harness plug that goes to a small socket above the multi cd socket on the back of the radio. Without the amp you will have almost no bass. With the amp you will have very good sound from your stock looking radio. The normal 2008 Ranger radio connections for ignition, clock power, lights, dimmer, speakers and go through the stock plug to the Mach. My rear speaker wires ended at a connector under the drivers seat not at the grills above the back seats. The amp and subwoofer are behind the left jump seat.
The Mach RDS radios do have a display problem caused by resistors mounted too close to the display power supply board. The heat causes the solder on the surface mount components to crack in the area around the hot resistors. Resoldering the surface mounts and the large resistors will restore the display. Raise the large resistors as far as possible from the board and add holes to the tin shield to keep them cooler. These radios can be fixed and I think mine was worth the effort to get that subwoofer sound. The Expedition and Lincoln Navigators have a larger subwoofer.
Last edited by grdbrg; 03-11-2014 at 02:20 PM.