Why does the car not start when the stop horn fuse is blown?

You Acura needs to confirm that a few systems are operational before it will allow you to start the car. One of those systems must be fed power through the stop/horn fuse. There are 1,000 places where a short could have cropped up to continually blow that fuse and you need to run that cause down. if you haven't had anything installed lately that might imping a couple of wires (ground effects, spoilers, stereos, radar detectors, remote starters etc) you probably need a dealer to try and find it. That can be costly. A repair manual might offer a troubleshooting checklist to assist or at least tell you where to look in terms of runs of wires that need to be verified. Good luck!

One common problem seems to be a short in a horn. I had this happen just recently and was able to solve the dilemma temporarily by just pulling the connector off the horn in front of the radiator and replacing the 20A fuse.

Have talked to 3 Acura service managers this morning and no one can answer the question and wouldn't even take the time to ask a tech. Honda makes good cars but their customer service is lacking.

Also curious why the horn circuit would blow the fuse when the button is not being depressed and why pulling the disconnect would make a difference? The high horn works fine by itself and the car starts.

According to the schematics for the anti theft system and the starter system, the Anti Theft System derives it's power from fuse #39 the Stop/Horn Fuse. The start circuit is completed thru the anti theft computer.