99 _=F-150 4x4 4.6. My anti theft light continues to blink after starting. Works normal with engine off. After starting, light blinks brighter and faster for about 2 min. then returns to normal eng off blinking. After about a mile, light goes out. Will this disable my truck during driving or what could be causing this. Thanks

 

Pats normally won't have any effect once the engine is started.
However if you see there is a problem it may prevent starting which is just a bad as if it were to stop the motor while running.
Turn the key to Run for a few minutes and see if the light flashes a 2 digit code.
If yes, post the code.
Good luck.

 

Fixed the problem. Somehow, this light is wired into the starting circuit. Last couple of days I noticed that my cranking power was going away till I had no current at all. Inspected the battery terminals replaced them and also cut back the insulation and exposed new wire. Put everything back in order problem solved.. Hope this helps somebody