[so2315]

I have a 2000 Windstar SEL. Just recently the horn confirmation upon locking the doors have stopped working. Everything works as it should with the key fob, doors all lock and unlock and the sliding doors open. I have no door ajar warnings and the hood light is not on when closed.
The horn used to chirp when I pushed the lock button twice, now it has quit working. Any ideas on where to start?
The lights also do not flash when locking. If I use the panic button, the lights will flash and the horn beeps. Seems like it should be a simple fix, but having no luck. Tried the reprogram the remotes with no luck. Also tried holding down both lock and unlock to no avail.