I have 2003 Mercury Sable that I bought about a year ago. I've had dead battery issues with it the whole time. It seems that if I drive it every day its fine but if I go a couple of days it won't start without a jump, then its fine until I leave it for a day or more. The battery and alternator have been replaced and they both test ok, and there's no corrosion or other connection issues as far as I know. Until now I assumed its my fault for not driving it enough, but I've been doing some research online and now suspect I might have a parasitic drain. The interesting thing is that my previous car, a 2000 Grand Am, did the same thing and it also tested ok. I had a brainwave yesterday when trying to charge it (it wouldn't charge by the way but was fine when it was jumped). It occurred to me that I've always kept the auto headlights on, even when the car is off. I can't afford to go to a mechanic and have the car tested for a drain, so I want to see if I might be right with my deduction that leaving the headlight switch on auto all the time is draining the battery. By the way, these are the first cars I've owned that had the auto feature.
Wednesday, January 9th, 2013 AT 7:58 PM