I purchased a new set of key fobs from Ebay and cannot get them to program. I apparently have some sort of dealer installed aftermarket alarm system. Instead of cycling the key, I have to push a small black button located under the dash. The horn will chirp 3 times to indicate it has entered programming mode. I can then push the lock button on each new fob and the horn will chirp once on each to indicate it has been programmed. After turning the key off to exit programming mode, the new fobs will not work. What is strange is the fact that I can program and deprogram the old fob using this method. The old fobs have the "FORD" logo embossed on them. The new ones don't but seller claims they will work with "any" Ford 3 button fob. Does anyone have any ideas on this? Oh by the way, it's on my 1999 F250 Super Duty.
I suspect that the old fobs are different than the Ford OEM ones. You might see if you can find the aftermarket alarm module and see if it has the name of the maker on it. You might be able to get fobs from them.