I took the car to a dealer yesterday to have some other things checked out and asked them about the LED and horn chirp at the same time. They didn't charge me to look, but their alarm specialist didn't have a chance to look it over, either. On first glance, though, it appeared that the LED box under the steering column is part of an aftermarket alarm system that was added on to the factory system. I have to bring it back in again for some things that there wasn't enough time for the first time, though, and at that point I'll have their alarm specialist check it out further.