I have a 98 Mustang GT conv. with the factory anti theft system with the coded key, remote and alarm. It uses a factory type transmitter. The theft warning light started flashing a few weeks ago, now the led double flashes instead of single flashes, the alarm now chirps only once when armed instead of twice and won't activate if the car is opened and the theft light flashes code 6 1. The dealer says it doesn't flash codes, but it is.... Any suggestions?