In this guide I will be doing my best to cover the Programming/Erasure for the Ford Transponder Keys, there will be three sections to this, one will cover early models, using a Red Master Key, the second will cover the Two Working Key system, and the last will cover the erasure of lost/misplaced keys from the Two Working Key system.
Programming using the Red Master Key (Early Models)
Different models enter the programming mode in different ways, for the MK1 Mondeo you will have to turn the red master key on and off five times in rapid sucession, removed that key and then insert the new key to be re-programmed and turn to the ON position while watching the red LED by the side of the clock, once the LED stays on constantly, the new key should be programmed.
For other models, such as the Fiesta, you only need to turn the red master key to the ON position once, then remove that key and insert the key to be programmed and turn to the on position watching the red LED by the side of the clock, once the LED stay on constantly, the new key should be programmed.
NOTE: Upto 15 keys can be programmed
Programming using the two working key system, (Later Models)
Assuming you have two working keys, (Working keys, means they start the car, not just open the doors), take both of them along with the new/replacement key, insert the first working key and turn to the ON position, remove that key, and repeat with the second working key, (This puts the PATS system into programming mode), now insert the new key within 10 seconds and turn to the on position while watching the LED beside the clock, once the LED stays on constant the new key should be programmed.
Needless to say it is advisable to check the new key after the system has had time to reset, (about 5 minutes)
NOTE: Upto 8 keys can be programmed
Erasure of Lost/Misplaced keys from the PATS system, (Two working key system only)
Assuming you have lost/misplaced one of your keys, but still have two other working keys, you can simply erase the code for the lost key from your system.
This has the added advantage, that should someone find it although they will still be able to enter the vehicle they will not be able to start it.
Take 2 of your working keys, and insert one into the ignition, turn it to position II, and back off and remove it, take the second and repeat, this puts the system into the learning mode.
Re-insert the second key and turn to position II, and back off, now take the first key again and turn to position II, and leave it on for at least 5 seconds, this will erase all the keys from the system except for the two keys used for the erasure.
Any other keys can no longer be used unless recoded