Reset the Theft Protection in a Ford Expedition
The passive anti-theft system (PATS) is installed on every Ford Expedition at the factory. While some erroneously call this system the factory alarm, it really is not an alarm system. The PATS system will arm itself if someone attempts to start the vehicle with anything other than the PATS key programmed to that specific vehicle. Once the system is triggered, the red light on the dash will begin flashing faster than normal and it will remain in this mode until either the proper key is inserted and turned in the ignition or 15 minutes has passed.
1. Get into the Expedition and insert the known correct key into the ignition and turn it. If you use a non PATS key, such as one that was cut simply to open the doors from an all-metal key blank, the system will remain armed. If the Expedition starts, then you have disarmed the PATS system. If not, move on to step 2.
2. Verify you have the right key. Ford PATS keys have large black plastic, or molded rubber, heads. Inside the head is a transponder chip that is programmed to a certain code so that the PATS transponder in the vehicle recognizes the key. It is possible for a PATS key to lose its programming, but highly unlikely. In the event you are certain you have the correct key, try to start the Expedition with the spare, if you have it. If the Expedition still refuses to start, move on to step 3.
3. Wait 15 minutes, until you see the flashing rate on the red light on your dashboard decrease to normal speed and then try both keys again. If this still fails to start the Expedition, raise the hood and disconnect the battery for 15 minutes, then reconnect it and try again. If, after that, you still cannot get the Expedition to start, you will need to have it towed to a Ford service department for further diagnosis by a trained technician.