Plug Wires. I Need To Know

Hi,I have a 1995 grand marquis .? is I took my car for a diagonis because the car lost lights, radio , directional lights, Turned out Ford dealer said the Control lighting module was bad .I found 5 of them 3 from junk yard and 2 from a factory which rebuilt and prggrammed them .I went back to the dealer with one of the module that I purchase from the junk yard to be programed result ford said the module was no good and tried 2 more I had and same result no good. Well turns out I checked the plugs that the module goes into with a tester some light up with the tester some did not, I left the module plugged and now the back lightss work along with brake lights, horn is beeping also. I believe Ford did not check the wires like they tolded me. I believe there is some kind of electrical wire that is bad which is causing this module not to work correctly. Please help me out to solve this problem thank you