I have a 1999 4/4 which is fitted with the Ford PATS (passive anti theft system ). Passive because the ignition key requires no battery for the system to work. Immobiliser's evolve and given the age difference of your car to mine this may be irrelevant. But on my car if the immobiliser is activated as on yours the immobiliser light flashes rapidly. However if you leave the ignition turned on after about one minuet the light goes out, then after a brief pause it flashes the light to give a two digit code. For example code 11 means no connection between the transceiver coil and the module. That is the coil around the ignition key barrel and the module, in my case the ECU since all of the immobiliser function is contained within the ECU. Code 12 no data received from the lock barrel pick up and so on. I have a list of 12 different codes for different problems. I have built an ECU test rig with a transceiver coil and immob light and tested a few of these codes and they work very well giving a good clue as to what has gone wrong in a situation such as yours. If you would like me to post the full list let me know.

Regards ZACH