Mercury Cougar Fuse Problem

I think that your talking about the trunk ?and your using the keyless entry key pad on the door correct? And the button is the inside trunk release? OK let's see when you use the keyless entry key pad do all the doors unlock using 3/4 button and the only thing not working is the trunk ?yes if so there's a broken wire or oxidized connection pop the button switch out by the hood release disconnect the plug examine the contacts inside for corrosion and clean with alcohol and lube with contact grease or pb blaster reconnect it and try it also check the switch for 12 volts and for continuity when the switch is pressed if none replace the switch if volts are good wires good and continuity good make a set of long jumper wires and alligator clips now go to the trunk and open it and unplug the connection check again for corrosion and broken wires clean and lube now using your continuity tester or volt meter with this feature check the wires for voltage and continuity and also use a wire from the + battery cable and the ground and see if the lock activates if it does function we have a problem with the wires before the lock or the driver door module connector maybe dirty and corroded or have a broken wire and I have instructed you to do this way because now it gets harder as mentioned if the lock functions from the jumper wire that's great if not change the trunk lock so if we have to check the driver door module you will have to take off the door panel to get to it and remember for the fuses they are called trunk or luggage compartment in the manual another thing if you use your keys to punch in your keypad code you may have damaged the unit all of the circuits for the door and trunk go through the keypad and the driver door module so do yourself a favor and make sure you write down everything you've done and we will take it from there so here's a summary of things to check ///fuse///push button switch by the hood release///the trunk lock///the keyless entry keypad///the driver door module///all wires and connectors and also the master power window switch because it maybe piggy backing a voltage for the circuit and a lot of times this will be the problem so remember your cars almost 20 years old and these are the kind of things that are now par for the course on an older vehicle corrosion and oxidation of switches wires and just overall worn contacts can all contribute to this symptom and I have to try to tell you everything that I can because I'm not there at the vehicle so it's all you so go slow write it down and we can eliminate certain things to get to the problem and just so you understand where the information is coming from I'm a taxi mechanic in nyc.with 50 years experience and I've seen a lot from the chariot drivers here between accidents causing broken wires to coffee and soda spilled on stuff while driving and when they drive through store fronts and wreck all the wires I'm the guy who puts it back together after they reared buses and trucks yikes so have fun learning and this all takes time so go slow and post back with specific information and we'll get to the problem some of these cars have 400,000 miles on them and they are crown Victorias and are ford's like your cat so your in the right place later good luck stephen

Suggest obtain a good volt/ohm meter and trace out your circuits. Sounds like a loose connection or broken wire.
Using the Volt/ohm meter will help you locate the problem. Then replace the bad part(s).
Remember to disconnect the battery before you make electrical system repairs. Follow the shop manual steps to avoid computer issues.