I changed out a bulb on the back of the cluster put it back together and hooked the battery back up. I'm now getting a fast blinking security Light. The truck won't turn over. Key will turn gear selector moves and all dash lights come on. Fuel pump also cycles. Had a lock Smith try to reset the PATS but he said his computer couldn't talk to the truck. Any ideas.

 

Welcome to the forum

Fast flashing theft light will, of course, cause a no start

So either a fuse was blown when you reconnected the battery or some connector behind the dash was disconnected or loosened during the work.

What I would do first is to disconnect BOTH battery cables
Touch both cable ends together and count to 10 slowly, drains capacitors and clears most memory from devices.

Reconnect both cables back to the battery
Test if PATS key works.
If you have a second key try that as well.

If you still have the fast flashing Theft light then start checking fuses.

If lock smith could not connect to OBD2 system then I would start with that fuse
Look in owners manual to see what fuse that is

If you don't have the owners manual you should be able to down load a 2007 manual from Fords website, I think they go back 10 years

 

Thx I'll try that.