Do the keys have a sender built into them? My 94 4/4 didn't but my S1 roadster from 2006 did. If that bit falls out the immobiliser will not be deactivated. Try comparing the key with the spare.
No just standard Ford keys, the immobiliser light does go out when the engine spins. Same with both keys.
Does the immobiliser work on the ignition or fuel?
Gordon
