I would suspect that you might find the solution in the owners manual, just look in the index under Alarm System. You could call your dealer and speak with a Service writer, they might be able to explain how to do it, or it might be a problem that the dealer would need to correct.
Good luck with that. I have a 2002 T and paid $400 on eBay for one; worth every penny even if expensive.
You might find it cheaper at Flying Spares.com. When I bought mine I had not known about that website.