1999 was the first year Rangers got PATS(passive anti-theft system), but I think only the V6 models got it in '99 4cyl models were 2001 I think
PATS requires an RFID embedded key to be used or fuel system will not work, the RFID "tag" in the key requires no batteries, there is an antenna(wand) around the key cylinder, when PATS key is inserted and turned on the PATS module sends out a Radio Frequency(RF) pulse thru the antenna(wand), this gives the RFID "tag" enough power to respond with it's unique ID number, the PATS module reads this ID via the antenna(wand) and compares the ID number to a list of IDs that have been stored in its memory.
If ID matches PATS module allows computer to operate fuel system.
Pats module and computer are a set, "married" at the factory, one will not operate without the other and if you swap one it must be re-married to work.
In later years the computer and PATS module were combined, and a starter disable relay was added, so engine wouldn't turn over along with fuel system disabling if PATS key ID didn't match.
If you have 2 "working" PATS keys(with different IDs) you can add a 3 or 4th PATS key yourself, you just need to have a PATS key cut to fit ignition then follow the steps to add it to PATS module.
If you only have 1 "working" PATS key, then you can't do this, BUT.........you can "clone" a PATS key, you can have the same ID number on "working" key installed on a blank PATS key, and since it is the same number it will work, it is great as a backup key, but since it is the same number it can't be used as 2nd key to add more keys to PATS system.
Ford dealers and Locksmiths with Ford software can add PATS keys to the system, this can only be done with computer and PATS module in the vehicle, so if you lose your last "working" PATS key you either need a mobile locksmith with Ford software to come out, or you need to get towed to a Ford Dealer
This often comes up when doing Explorer V8 swaps since explorers got PATS in '98, make sure you get "working" PATS keys with the Explorer computer.
Last edited by RonD; 11-24-2015 at 09:13 PM.