Gotta re program it. Turn your key in the starter to the on position ten times in a repeated motion and then unlock and lock the doors. Google it. I ha the same problem went through 3 batteries and finally heard about reprograming it and that's why it was!
1999 V6 Mustang Dark Satin Green , SR CAI, BBK 65mm Throttle Body, Screaming Demon Coil Pack, SR Lowering Springs, Pioneer Stereo, 2 12' inch subs and 1600watt amp, Green Calipers,