Originally Posted by oskiee6
well got reciever back from barry. the key is coded and works fine operating the central locking. however the alarm does not turn on/off. i have never switched it off on the box in the boot so bit confused. any suggestions would be welcome.
Do you know what it is that Tony actually did to you receiver? Did he 'virginise' it and program it with a new code or just retrieve the original code already stored inside it?
First of all, the alarm doesn't lock or unlock the doors...it's done directly from that receiver in the roof. When the receiver receives a recognised signal from a known key it will send one control signal to the central locking and another (separate) control signal to the alarm box in the boot.
The signal sent from the receiver to the alarm box is a serial data communication (i.e. it is not just a simple on/off signal). In the data is a code that the alarm box is expecting. This expected code is actually the code of the original key that was first used to activate the alarm before the car left the factory. The first time a key is used to arm the system (and lock the doors), the code of that key is stored in the receiver and also sent to the (virgin) alarm box where it is also stored. This then means the receiver and alarm box are "paired" by way of that code and the alarm box will only arm/disarm if it receives that known code. Regardless of which key is used to arm/disarm the alarm in the future, it is always the code of the first key ever used that is sent from the receiver to the alarm box.
If Tony has wiped the existing code in your receiver and replaced it with a new one, the alarm box isn't expecting that new code so will no longer respond to arm/disarm signals sent from your receiver. The only solution is to either wipe the code stored in the alarm box so it becomes a virgin box again (if that is actually possible), or get a new alarm box. With a virgin alarm box, it will then pair itself again with the receiver on first use.
The whole Alarm / Immobiliser setup on these cars is a complicated beast. I know it's good to know that your alarm / immobiliser system is as secure as possible but sometimes I can't help thinking that Alfa have maybe gone a bit too far and just caused too many unnecessary headaches for the real owners of the cars
It is worth speaking to Tony again because maybe he has the know-how to also virginise the code stored in your alarm box.