156 key suddenly won't disarm alarm and operate central locking
Suddenly the key to my 03 Alfa 156 Sportwagon Selespeed does not disarm the alarm or operate the central locking. When you press the main key button the light still comes on as if it is working normally, but nothing happens, no indicators flashing or bleeps etc. The smaller button on the key does however still operate the tailgate opener, though this does not seem to spring open as much as normal. If you open the driver's door manually with the key and open the door, the central locking doesn't operate and only that door is opened. The alarm then goes off when you get in (motion sensor I presume) and the car turns over but will not start. There seems to be power to the dash and headlights as well as the alarm so the battery seems to have power. For some reason the key is not disarming the alarm OR turning off the immobiliser, though clearly it is talking to the car as the tailgate opens.
Does anyone know what the problem is? Is there some kind of reset I can do? I have tried holding down the main key button for 80 secs as advised on another site, to no avail.
I have also replaced the battery in the key in case it was just too weak (though the failure is sudden not intermittent over the past few days) - this has had no effect.
I have spent the last hour searching the forums here but can't find a solution, hope someone out there can help?...