Help!!!!!!!!! Ford Alarm/keyless entry

it does seem that vehicle has the ford factory security in it. I don't believe the wire under the hood is for a siren as factory alarms rarely have sirens and usually just use the horn honk and flash the parking lights. Also on the steering column the led may be factory or that may be a dummy led that turns on when the ingnition turns off, can't tell without seeing where it is hooked up to. I don't beleive you need factory remotes for the factory security system to work. Try this, with your windows down, hit the power lock twice and wait 15 minutes, then put your hand through the window and open the door up with the handle, not hitting the power unlock button, just manually open the door. This should give you what your looking for.

Just buy an el cheapo siren from Autozone and wire it up to see. The control box looks genuine, but my guess is that it's a Ford system installed after the fact. I wouldn't think Ford would put an indicator light where yours is mounted.

From your pictures the security system in the Mustang is NOT a factory-installed system, but instead an Ford accessory security system. It was put on after the car left the assembly plant. The factory systems use the car's horn as the siren, the accessory systems have a siren that looks like a bullhorn, and is usually mounted under the hood. Those two wires that appear to be cut probably went to the siren. Your remote on your keyring-if it has only 2 buttons-either marked "A" and "D" (arm/disarm) or "L" and "U" (lock/unlock)- that style is from the accessory system. The factory remotes use at least 3 buttons (lock/unlock/panic) sometimes 4 buttons (lock/unlock/panic/trunk release). The little red LED on the dash is a "valet" button. You can use it to prevent the alarm system from automatically arming itself, and enabling the starter cutout. (For example-you go the the gas station-by the time you are done filling up, your alarm will have automatically armed itself and you will have to use the disarm/unlock button on your remote to start the car.
By the way, I work at a Ford dealership so if you have any other questions, let me know. hope this helps a little bit.

You'll need to visit the dealer and purchase a remote specifically for a dealer installed keyless entry kit as the factory option remotes will not work.
Programming the add on remotes is a pain too.....

Hey 808,
Sorry it took so long to get back to you. If you haven't gotten an answer yet- you can get an accessory transmitter from your local dealer (part # E9AZ-19A361-F) and program it to your system. There's instructions on how to program the transmitters in the box with the transmitter. The programming procedure depends on the system you have in your car. From the looks of your pic you have the 500 or 600 series system installed in your car. They're pretty simple to program. Just make sure you get the accessory transmitter (2 button), not the factory (3/4 button) transmitter. As for the connector in the picture, it kinda looks like the EEC IV diagnostic connector. That connector shouldn't go into the security system module, but instead should be wired into a mondo wiring harness that goes over to the passenger side and into the EEC IV processor.