The "Alarm Horn" is the cars actual Horns! Controlled by Fuse 5 in the Engine compartment Fuse Box. If this question is related to an alarm fault, the alarm is controlled by Fuse 6 (>2002) of Fuse 1 (2003 models) in the Interior Fuse Box, behind the drivers storage box to the right of the steering wheel. Pull storage compartment out and manouver up to remove. There are other postings available regarding the Alarm Faults on the web, Google : rover 45 alarm fault.
Iain S., December 2008
