help my siren doesnt make noise anymore

i have a 1992 mustang i bought from someone and the siren comes in and out it works sometimes and doesnt anyone know what would make this happen???? how can i fix this??? i dont know much about alarms so i dont know what to do but i know a lot about cars and electronics so if someone tells me what to do i can fix it i just dont know whats wrong do i need a new siren box? a new wire to it? anyone know? thanks for reading

Sounds like a faulty ground.

take the power and the ground wires and touch them directly to the battery.. if the siren works it will sound.. if not you need a new siren.. if it works then troubleshoot from there.. check your connections, both ground and power...