Mercury Keyless entry remote programming (sometimes called installation) and activation is a simple process. Actually, despite of the common name - remote programming, the process involves training the vehicle to recognize a new remote you purchased. This remote programming procedure should not take more then 1 minute if followed successfully. If it did not work or you missed a step, try programming your Mercury keyless entry remote again. You cannot brake anything.
MERCURY KEY FOB REMOTE PROGRAMMING INSTRUCTIONS
Turn ignition from OFF to RUN (as far as you can go without cranking the engine) 8 times (one turn is from OFF to RUN and back to OFF) within 10 seconds, with the 8th time ending in RUN (8th time you only go from OFF to RUN and stop there) (do not start the engine). All doors will lock then unlock to confirm remote programming mode. Within 20 seconds, press any button on 1st Mercury remote transmitter. Door locks will cycle to confirm keyfob programming. Within 20 seconds, press any button on 2nd car remote transmitter (up to 4 keyless entry remotes total possible). Turn ignition to OFF. Locks will again cycle to indicate end of programming mode.