2000 Expedition Eddie Bauer AWD 161,000 miles


At first what i believed to have been a PATS issue has now been thought to be an electrical issue.
I went to get in my truck a few weeks ago, when i turned the key it crunk, then died after a second. If i recycled the key if would try to start but never crank. Later that night i tried it again, when i turned the key to run, all the lights came on (headlights,tailights,interior lights) and the horn blared for about 10 seconds. I quit then because it was midnight and did not want to wake the neighbors.
The next morning, the problem diasappeared........until exactly a week later.
Same issue, this time i noticed the guages would not move, the electric seat would only move forward, the doors would not unlock from inside, and the keypad on the door would not work also. Unplugged the battery thinking i would reset the PATS, but it still continued for 2 days, with all those symptoms, add in the horn blaring with all the lights on every few times i would try.
The issue then went away for a couple weeks then a week ago came back and since has not left. The keyless entry no longer works, i think the code deleted itself when i unplugged the battery.
Someoe said they believed it was the ignition switch possibly to blame so i replaced that, and after a couples tries, it worked. Until 8 hours later when the problem was back again and im back to square one.
Ive also checked all fuses and swapped all the relays around.



Please Help ME without having to throw hundreds of $$$$ at this thing

 

How old is the battery?