1997 Cadillac Deville

Testing parasitic drain involves placing an ammeter inline between the negative battery cable, and negative post. After about 20 minutes, if the drain is excessive(greater than 20-30 mA), than you start by removing fuses one at a time, to determine which circuit is causing the drain. It could be something stuck like a switch or relay, or something keeping the system from going to sleep. It can be somewhat tricky to isolate. As far as guessing what the cause is, it is just that, a guess. Do a visual for something obvious, stuck lumbar or seat switch, lamps on in the glove box/underhood/rear compartment. Also consider if the vehicle is equipped with any aftermarket devices, such as an alarm, or stereo. Often times an installer can induce a battery drain by tapping into the wrong circuits.