Tail lights and everything on that fuse quit working but the fuse is good. Would the culprit be a wire going IN or OUT of that fuse?
It could be but I would try another good fuse first. If there is a short in that circuit and the circuit is energized when you install a new fuse, the new fuse will immediately blow as well. Remove the "good" fuse you installed and make sure it is OK by attaching an ohm meter to it to check continuity. If is is good and you still have no power in the circuit, then proceed to check the wiring. Start by seeing if there is power to the inbound side of the fuse socket. If power is present then you know the problem is between there and one of the accessories on that circuit. Good luck.
Turns out it isn't a bad wire. Cantor answered this same question about a year ago. He said it was the headlight switch. He said to test by pulling out the knob until it sits between park lights and headlights. If the rest of the lights work again, that's it. I tried it and that's it. Thank you so much for taking the time to try to help.
Search Mercury Grand Marquis Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Mercury Grand Marquis Experts