It's not as easy as just pulling a fuse because all the dozens of computers talk back and forth with each other. If it was this easy, thieves could disable it too. Also, unless there is a problem with that one computer, you'll still have all the others to consider, and on Cadillacs, that can be up to 47 computers, the last I heard. About two thirds of them draw a small current all the time when the ignition switch is off.
You have to be more specific about draining the battery. Does the battery run dead in a couple of days or a few weeks? The industry standard for many years has been the maximum battery drain to keep all the computer memories alive is 35 milliamps, (.035 amps). Chrysler says at that rate, a good, fully-charged battery will be able to crank the engine fast enough to start after sitting for three weeks. Cadillac is one of the notable exceptions because they have even more troublesome electronics than most other car brands. They allow up to 50 milliamps.
You can expect to have to drive the car at least about once every two weeks to keep the battery charged, and those trips need to be for a good 20 to 30 minutes. With a battery that's three or four years old, it won't have as much capacity left so you might need to drive the car once a week. If you don't want to do that, consider connecting a small solar-powered trickle charger. They've become popular in the last few years just because of this problem. The insane engineers at Ford have really gotten out-of-hand. They are so proud of all the electronics on their cars, but they never talk about all the problems due to the fact normal car-related heat, cold, and vibration are the worst environment to plant all this stuff.
If you have a power outlet or cigarette lighter that work when the ignition switch is off, you can plug the charger into that socket, otherwise you would need to connect it right to the battery. You can also just use a portable battery charger periodically, but when I've done that with one of my cars, I often forget about it and end up over-charging the battery. On most of those smaller chargers their lowest setting is 2 amps. That low rate will take a real long time to fully charge a dead battery, but it's more than high enough to over-charge it if you forget it for a week or two. These are okay if you plug it into a timer or if you don't forget to unplug it after a night or two.
Sunday, February 8th, 2015 AT 9:54 PM