Anti-Theft system malfunction / cannot start truck
 

The anti-theft (alarm) system on my 98 Expedition suddenly stopped working a few days ago. The red light for the alarm is not even lit up, and nothing happens when I press that button, or when I use my remote to attempt to arm/disarm it. Worse yet, the truck will not start! When I turn the key over, I see all the typical panel indicator lights, but I cannot turn the engine over. Every other electrical component in the vehicle works fine. I thought that maybe the battery was just low, but I still could not start the truck by using jumper cables. The battery terminals are quite clean. I tried pressing the alarm reset button near the accelerator, but that had no effect. Any thoughts??

Did you try starting it when in neutral?

Tried starting in neutral just now. Nothing. Same behavior as before. No sounds at all... no clicking, no grinding, nothing at all.

In that case I'm sure the 'no start' issue has to do with the alarm not functioning. The alarm must energize a relay to enable the starter. It's likely wired this way so that if someone were to disable the alarm by cutting the power to it, they still could not get the engine started.

Have you checked for a blown fuse that might be powering the alarm?

Checked all fuses in the main fuse box and they all look good. I read somewhere that there may be another fuse or two for the alarm system, in-line and not readily accessible to me.

If your '98-'00 Expi has the Ford System 3 (or 4) Security System it has a small red light (Valet Button) below the steering wheel, sort of between your knees. Look directly behind that little red light on it's wire loom that goes up under the dash, there is a very small Micro 'Emergency Override Button' about 3" behind the Valet Button on the loom. You'll need a flashlight.
When you find it, insert the key and turn on the ignition so all the dash lights are on - then push the Override Button, the Security System should now be disabled and the car should start. You may have to hold down the Override Button while cranking the engine over.

"Fixed"!
 

Thanks for the advice. After trying everything advised (plus other tips read online), I ultimately had to have my truck towed to the local Ford dealer/repair shop. They quickly found that someone had, in fact, attempted to steal my truck from my driveway, by cutting the alarm wires. (And a few other wires!).

Cost to repair was prohibitive, so they disabled my original alarm system and advised me to purchase a new one locally for less money.

Thanks to everyone for all the advice.

You saved my bacon stuck at the post office parking lot by suggesting to start an older expidition in nuetral. Thanks man!