[shorod]

Interesting. It appears from the service manual that the anti-theft system has its own horn, not shared with the steering wheel button horn. My expectation would be that the horn honks not on the first "lock" press but if you were to push the "lock" button a second time shortly after the first press you would get the honk. I would not expect you to get a honk when disarming/unlocking.

Does the horn honk when you violate the perimeter? I think you can do this by rolling down a window, arm/lock the system, then open the door from the inside door handle. If the horn honks this way, you know the horn is physically and electrically fine.

The bubble like object in the center of the dash I believe is the sunload sensor for the EATC if you had it. The autolamp sensor appears to be located in the proximity of the headlamp switch.

-Rod