PATS - Passive Anti-Theft System

Last update:

07/30/2007

Ah, those innocent days. Car theft was very rare and almost no-one even removed the keys from the ignition.

But the past is a foreign country, they do things differently there.

The juvenile car-stealing craze of the early nineties meant that those complacent days were gone forever. Even with much better locks, the thief soon realized that all he needed to do was to smash the ignition surround, pull the electrical switch from the back of the ignition barrel, and turn the slot in the switch with a screwdriver. Instant ignition!

The hotter the car the more they became a target, until it was virtually impossible to insure a Sierra Cosworth or an RS2000. Any car which was particularly vulnerable would be stolen by the hundred, ‘hotted’ in races and wheelies with other stolen cars until they crashed or seized up and became a smoking ruin.

Something had to be done, and so quietly that you can hear the deafening silence, Ford has done it. PATS is the answer.

Passive Anti Theft System

There is some confusion about what PATS is, and what it does. It is not part of the central locking or the alarm system, although it does share the red LED on the top of the dashboard. It is designed to be completely transparent so that it requires no action at all on the part of a driver, and always remains active, even if the doors are left unlocked and the alarm is off.

The PATS system was first a separate module mounted beneath the dashboard, and later became part of the engine management system, and is connected to a transceiver mounted around the ignition barrel. When the ignition key is not present, PATS disables all of the EEC V engine management, and on some models the starter as well. The PATS receiver awaits an ignition key with a transponder (the little red tag mounted in the key) which matches the code that PATS recognizes. This is the clever part: even if a key is an exact physical match with the ignition lock and the key is turned, PATS checks the transponder code and if it is not recognized the engine is dead.

So the spotty dork who breaks in to steal the car smashes the steering shroud and rips away the electrical connection at the back of the barrel is wasting his time. The ignition switch itself will turn, but the engine management system has not received the OK from PATS and the engine remains stubbornly silent.

AHA, I hear you cry, what if I replace the PATS module? Well, apart from the expense, you will need the WDS 2000 diagnostic system and expert time in order to program PATS to the new system, and no main dealer is going to do that without checking the validity of the request, end of story. On later variants, the PATS is built into the EECV so that has to be changed – and yes, you need WDS to reprogram it.

What, cries another clever dick, if I remove the PATS fuse? Same thing, dummy. PATS has not given the ok and the EECV management system remains completely inert.

Programming new keys
The system itself assumes that there are three keys programmed into PATS. One is a red key, the master, and two slave keys, which are black and will have a red dot. The red master key should be locked away in a safe place and only the black keys should be in daily use. If a key is lost, the red master key can be used to program a new key. The following sequence is noted in the vehicle handbook.

1. Obtain new key from main dealer ordered using the vehicle key number.

2. Insert red master key into ignition and turn to position II. When the red LED comes on switch off and remove the master key.

3. The LED goes off and then comes on for 2 seconds. PATS is now in programming mode for the next ten seconds.

4. Insert the new slave key. The LED will come on and go off to confirm that the key has been programmed. Switch off and remove the new key.

In the event that the red master key is lost, then a new one can be ordered using the vehicle key number. Be prepared to prove that you are the registered keeper of the vehicle because otherwise the main dealer should refuse. This master has to be programmed by a Main Dealer using WDS, which clears the PATS module memory and reassigns the new master. Once that is done, the old slave keys need to be reprogrammed as above.

Fault Finding
Although the red LED is used for the alarm and the PATS system, PATS has priority, and the LED can be used for fault diagnosis. The LED should always go out about three seconds after ignition on.

If there are less than three keys programmed into the PATS module the LED will stay on for one minute with the engine running, but if the LED flashes after that then careful attention should be paid because it may be a fault code.

The following checks can be made without WDS:

If the LED illuminates for 4 seconds but the engine does not crank, PATS is working correctly and there is a fault elsewhere. Try starter solenoid or battery. If okay go to main dealer.

If the LED illuminates for 4 seconds and the engine cranks but does not start, PATS is working correctly and the fault lies elsewhere. Check the Fuel Cut-Off switch. If okay go to main dealer.

If none of the above checks resolves the problem then the system will need to be connected to WDS at a main dealer for a diagnostic check.

If the engine starts normally but the LED stays on, wait for one minute. The LED may then flash a code 2:1. This is showing a ‘fault’ that there are less than 3 keys programmed into PATS. One of more keys need to be programmed to stop this code.

Any other code needs referring to the Ford main dealer.

Do remember
One last thing. You would do well to remember that your Scorpio can be stolen – if the key is taken first. Consider storing your car keys away when they are left in the home, because any burglar will jump at the chance for a free ride – and he’ll use your car to load up your household goods before he drives off and the next time you see your Scorpio it will probably be a burned out shell.

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