on the crown vic, passenger side there is a rubber plug in the non cvpi cars such as mine, with a little help from someone you can actually "poke" a hole in this rubber with an awl, coathanger, or any small sharp pointed instrument, then guide the wire through the firewall to the battery, I did this with mine with no problems, I ran both the positive and ground straight to the battery this way, with fuses on both + and -. Theres no need to run any wires outside the door jams on these cars, I was frustrated myself at first, but crawl up under the dash with a flashlight, you see what Im talking about, good luck to ya