96 Cavalier - battery looses charge

Will not consitantly hold a charge. Horn started blowing late at night after it sat up for a couple of months, pulled the line to it. Since then have recharged the battery, didn't hold. Then replaced the battery and alternator. Still loosing charge on battery when parked, but not all the time. It went a couple of months with out any problems, then lost charge over the weekend. Alternator and battery test good. Any ideas or things to look for?

Get a 12volt test light disconnect the battery ground. Hook the connection to the ground wire touch the battery neg. terminal. If the light lights you have a draw on the system. Pull a fuse and check again if it still lights try another one, check each fuse until you find the problem area. It could be a relay for the fuel pump or fan,or other relay also.

Thanks for suggestion. Will give it a try when she brings it back home and will post the results to the test.