Found this.....
Re-Synchronising Foxguard Alarms
Mar 96
Foxguard have found that a large proportion of returned F1-11 units are not actually faulty but simply out of synchronisation with the Radio Key. The F1-11 uses a random encryption antiscan grabcoding system. If the Radio Key is operated out of range of the car the key wilI transmit a coding signal but the receiver in the alarm will not recieve it. If this happens the coding in the Radio Key moves on but the unit will not. This will cause problems if the Radio Key is regularly pressed and released while out of range.
If the Radio Key no longer operates the alarm systern, try the spare one. If the system is operating correctly this indicates the first remote is simply out of synchronisation. It is possible to resynchronise the Radio Key:
Stand next to the car.
Press the left hand button on the Radio Key, the LED on the Radio Key will become solid.
Keep the button depressed for at least 3-4 seconds.
Release the button and immediately press the button again for 1-2 seconds.
The Radio Key is now back in synchronisation with the alarm. You may have to try a few times before the system will respond correctly, if you don't do step 4 quickly enough - the button need only be released for a split second.