Cadillac Repair: 1990 cad bettery drain, negative battery cable, amp meter

Question
battery drains over night on 1990 cad coupe deville

Answer
The FIRST thing you need to do is to see how many AMPS the vehicles electrical system is drawing from the battery when everything is turned OFF as if you were leaving it set overnight and put an AMP meter between the negative battery cable and the battery terminal and see if the system is drawing over 1/2 amp.