Funilly enough I've been thinking the same myself. My alarm goes off when I turn the key in the glove box. The only way round it I've found is to make sur ignition is off, get into the car making sure all doors are closed, then turn the alarm on. I then do the reprogramming sequence and my alarm then works (sometimes. The longest its worked is about 2 weeks
I've been thinking of getting a Toad as thats what I had fitted on the Punto. Theres a brand new one on ebay for £145. I'm tempted, just need to find someone to fit it cheaply
I have similar problem I suspect its because the key tranmitter has failed with the alarm in the on state. Mine has a new key but all the problems you describe. Is there a chance you are in the same state? I was thinking of a new alarm as well but interfacing it with the existing components is complex, particularly the immobiliser side but not impossible - I think!
A couple of months after I first got my 155, the alarm packed in, so after a word with my local dealers tecnician, I checked the connector block behind the drivers side headlamp. The whole thing was so badly corroded I had to cut and re-join all the wires. Haven't had a problem since.
I've got the same alarm as Andymac, but it cost me £120 off the internet !!!!
Have to fit it myself obviously, just can't be bothered to do it. Everything is in place, just need to connect the wires !!!
It has a seperate immobiliser, closes your windows (and sunroof if you wire it). The alarm also has a backup battery in it so if the power is cut or the battery goes flat it will still work.
On the non-working alfa alarm front, I've studied the repair manual, and found that instead of farting around inputting the 4 digit code, I've read that if you hold the small button down in the roof receiver, then press the fob button once, it re-memorises it. I've just done it and it has worked (maybe it will lose it I don't know).
I do have one question though. The re-programming proceedure asks for a 4 digit code. I have one on a credit card sized card, but I'm now thinking this is for the radio code. In tha manual, the alarm code is shown on the small plastic tag. I have a small plastic tag, but it has 5 digits on. I'm confused