Most of the "Ford" brand alarms were Code Alarm. If it's anything like the two "Ford" ones I installed a few years earlier, it will have an indicator somewhere on the dashboard. The button under the dash will be the disarm button and will turn the alarm off by turning the key to the on position and pressing the button (should you happen to set it off). Great if the transmitter battery has gone dead. The indicator light on the dash is also the valet switch. It should be a pushbutton and it should be blinking when the key is off. While the key is off, press the indicator/button for two seconds. It should stop blinking. Now, when you press the arm button on the remote, the car should chirp twice. The first time locks the doors and tells you it received the command, the second time tells you all the sensors are clear and the system is now armed. It should chirp once when you disarm and unlock the doors. The shock sensor you found under the dash should be a two-stage. With the alarm armed, you should be able to get the alarm to chirp a warning if you thump the car near the front door. Thump it too hard or often and the alarm should go off. While the car is in valet mode you basically have a remote entry system.
As I said, the ones I installed were a few years older. Hope this helps.