You must have all remote entry transmitters (maximum of four) available before beginning this procedure. According with the Mariner Owners Manual
check this procedure to reprogram the remote entry transmitters:
1. Ensure the vehicle is electronically unlocked.
2. Put the key in the ignition.
3. Turn the key from the 1 (LOCK) position to 3 (RUN).
4. Cycle eight times rapidly (within 10 seconds) between the 1 (LOCK) position and 3 (RUN).
Note: The eighth turn must end in the 3 (RUN) position.
5. The doors will lock, then unlock, to confirm that the programming mode has been activated.
6. Within 20 seconds press any button on the remote entry transmitter.
Note: If more than 20 seconds have passed you will need to start the procedure over again.
7. The doors will lock, then unlock, to confirm that this remote entry transmitter has been programmed.
8. Repeat Step 6 to program each additional remote entry transmitter.
9. Turn the ignition to the 1 (LOCK) position after you have finished programming all of the remote entry transmitters.
10. The doors will lock, then unlock, to confirm that the programming mode has been exited.
Note: If all remote entry transmitters are not present during the programming procedure, the missing transmitters will not work with the vehicle following programming.