You cannot reprogram it. A dealer can get you the Master Code if you've lost it.
thats my question to you
You cannot change the master code. You can add a personal code by following the directions in the owner's manual but you will need the Master Code to do so. It's usually on a sticker on one of the Trunk Life Rods. If it's not there, a dealer can retrieve it for you.
To reset the keyless entry system on a 1997 Mercury Grand Marquis, start by disconnecting the vehicle's battery for about 10 minutes. Then, reconnect the battery and enter the vehicle. Press the "1" and "2" keys on the keypad simultaneously, which should reset the system. After this, you can program new codes if desired.
Ou812
Underneath the trunk lid
If the keyless entry code sticker is not located in the trunk of a 2002 Grand Marquis, it may be found on the owner's manual, in the glove compartment, or on the back of the keypad itself. Additionally, the code can sometimes be retrieved by a Ford dealership or a locksmith with the proper tools and access to the vehicle's electronic systems. If these options are not available, consider checking for any hidden locations in the vehicle.
Look on the trunk lid support arm.
Check inside the trunk, on the lid arm.
look on the trunk hinge there should be a sticker with the code on it
Usually on one of the Trunk Lift Rods.
There should be a sticker on the underside of the trunk lid - that's where it was on my 92 grand marquis
Mine was under the trunk lid. When you open the trunk you can see it up underneath towards the back. A white sticker with 5 black numbers on it. '94 Grand Marquis