Mercury 2000 Grand Marquis Owner's Manual page 77

Controls and features
Automatic door locks can be turned on/off with the keyless entry keypad
through the following procedure:
You must complete steps 1-5 within 30 seconds or the procedure will
have to be repeated. If the procedure needs to be repeated, you must
wait 30 seconds.
1. Enter the keyless entry keypad factory code.
2. Within 5 seconds, press and hold control 7/8.
3. Within 5 seconds (while holding down control 7/8), press and release
control 3/4.
4. Release control 7/8.
The door will lock/unlock to confirm the feature has been disabled. Once
disabled, the feature can be enabled by repeating the same sequence.
Automatic door locks can also be turned on/off through the following
procedure:
You must complete steps 1-7 within 30 seconds or the procedure will
have to be repeated. If the procedure needs to be repeated, you must
wait 30 seconds.
1. Turn the ignition key to ON.
2. Press the power door unlock control on the door panel three times.
3. Turn the ignition key from ON to OFF.
4. Press the power door unlock control three times.
5. Turn the ignition back to ON.
6. Press the unlock control once. After a five to ten second delay, the
door will lock/unlock to confirm successful programming.
7. Turn the ignition to OFF.
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