on etis it says:
Principles of Operation
The passive anti-theft system (PATS) uses radio frequency identification technology and a unique encryption code to deter a drive away theft. Passive means that it does not require any activity from the user.
Encoded Ignition Key
The PATS uses a specially encoded ignition key. Each encoded ignition key contains a permanently installed electronic device called a transponder. Each transponder contains a unique electronic identification code which may be any one of millions of combinations. Each encoded ignition key must be programmed to the vehicle's PATS control function within the powertrain control module (PCM) before it can be used to start the engine. There are special diagnostic repair procedures outlined in this manual that must be carried out if an encoded ignition key needs to be changed.
The PATS transponder key is identified by a blue insert. Previous PATS transponder keys that have a red insert are not compatible with this vehicle and must not be used.
Only Ford approved ignition keys should be used as some aftermarket encoded ignition keys not purchased from a Ford approved source may fail to operate especially at extreme temperatures.
NOTE: If a non programmed key has been used, further key reading is inhibited for 20 seconds. During this 20 seconds, no ignition key will start the engine.
A minimum of 2 encoded ignition keys must be programmed to a vehicle in order for the engine to start. A maximum of 8 ignition keys may be programmed to a vehicle. The PATS control function within the PCM will enter Anti-Scan Mode if an attempt to start the vehicle with a non programmed ignition key (with the correct mechanical cut) is made.
PATS Control Function
The control functions are contained in the PCM. This module carries out all of the PATS functions, such as receiving the identification code from the encoded key and controlling engine enable. The PCM initiates the encoded key interrogation sequence when the vehicle ignition switch is turned to II or III. When the key is turned to the 0 position, the PCM will remain powered up for approximately five seconds. This is the maximum time allowed for the insertion of a second key to initiate the customer key programming sequence.
The transceiver module communicates with the PATS encoded ignition key. This module is located behind the steering column lower shroud and contains an antenna connected to a small electronic module. During each vehicle start sequence the transceiver module reads the encoded ignition key identification code and sends data to the PATS control function within the PCM. No re-initialization needs to occur with the removal or installation of a new PATS transceiver.
hope that makes it a bit clearer. looks like the PATS IS incorporated into the ECU/PCM
mate I'd take it to either a good auto-sparky,or to another Ford dealer. When you told me your mate said to look for the module etc,I thought if you went to Ford as a customer,they wouldnt say that. Their IDS/VMM should be able to pinpoint exactly whats up. Hell I know guys on another forum with IDS that'd definitely crack it,but theyre in another country.
ps:Ive PM'd you the self-test guide & wiring diagrams for the PCM/Transceiver. As I said if you're no good with a multimeter,an auto-sparky would suss it out