Cadillac Repair: Starting a1994 Cadillac DE VILLE, cable nut, battery cables

Question
I enstalled a new battery the same size as the old.When installed every thing works but when i turn the key to start every thing goes off.I unplug the battery then replug the cables every things works.But the same thing happens again when i turn the key

Answer
Hi Thomas, Make sure both battery cables are tight. Then make sure the black cable is tight on the engine and the red cable is tight on the starter solinoid. Make sure you have the neg. battery cable disconnected before trying to tighten the battery cable nut on the starter. You could have a bad ignition switch. Did everything go off with the old battery also? Let me know if you need more help. Bill