I have a 1997 Ford Expedition that wont start. I put the key to the on position and the anti theft light starts flashing . I have no idea what could have enabled the anti theft system. If anyone has any helpful information it is greatly appreciated

 

Any clicking sound coming from the dash area?

If the battery goes flat, the theft light will flash and usually the dash relays will click. Sure the battery is hot/charged? Tried a second key?

 

Had the same issue with my 2000 Expedition. Twice, I could get it to start after unhooking battery from system. Third time, it died while in line at a Jack in the Box Drive Thru and could not get it to fire. The coded 1:6 flashed, so I towed home and read everything I could about the problems (at this sit,e and others) with this type of Security System. Decided to go thru electrical system (battery, fuses, etc.) and see if anything could be done to fix easily. All was good and still did not start. I decided to goof around and see if I could get it to start by resetting the Fuel Pump Shut Off. Reset the Shut Off, locked and unlocked doors and followed Ford manuel concerning Fuel Pump Shut Off. To my amazement, it worked. Drove around town, shut off and it restarted. Went 30 miles to get a copy of key (only had one) and when I turned off engine at Locksmith, it would not start. He ran through his machine and many codes appeared and 1:6 flashed. He gave me many scenarios of what it could be (computer; ring that is part of Key Cylinder; etc.). Apllied the above steps to try and start and it restarted. Got home and began to check steering column and key cylinder. If theft system came on and could not start car, I would take key out, reposition steering column and reinsert key. This would fix problem, temporarily. When it happened again, I would slowly reinsert key, and then this would help also. So, the bottom line with my issue is that the problem lies in the key cylinder ring to send signal, or there is a short somewhere in the steering column. If there is someone with an easy fix, please post, since I do not want to have to give Ford anymore money on this FAULTY security system.
P.S. I am to understand the flash codes for the security system, especially for 1:6, can be a generalization for something that is either big, or small. But nothing specific.

 

there is no clicking sound, and the battery is completely charged

 

I am having the same problem and i do hear a clicking sound. Have to disconnect battery to reset and then it still wont work. Sometimes takes days to reset

 

Welcome to the site..

Any checks done on battery reserve/condition? It's age?
Eventually starts, or repeats the clicking condition?

Battery static/uncabled tested? Charged and a 12-24 resting voltage test?