Horn Randomly Going Off

[wisemk]

Hi, my Elise s2 has just developed this problem. The horn gives a short blast every 5 mins or so. Has anyone any ideas as to what could be causing this? I have checked all of the Alarm switches and they seem to be functioning. The car runs ok but the horn still goes off whilst driving. The only way I can stop it is to disconnect the battery.

[wisemk]

On further investigation the horn is going off exactly every 1 min 28 secs. Removing the Horn relay obviously stops the horn. I assume that something pulses every 1 min 28 secs and is shorting to the horn relay. I have contacted the alarm people and they state that the alarm system is not wired to the horn of the car. Does anyone know what pulses every 1 min 28 secs? When I get time I shall be removing the fuse panel and relay panel to see if I can see the short.