Contour Enthusiasts Group Archives Forums General Troubleshooting Weird Electrical Problem

I have a 1998 Mercury Mystique LS at 91,000 miles and the battery keeps going dead. A CEL was on for a while but then the code got cleared when the battery died again. I took it to the shop and they tested the alternator (which I replaced last November) and it was fine. They replaced the battery but then it went dead again the next day.

Any ideas what the problem could be?

I had the same problem. There is a huge fuse on the firewall behind the intake manifold that blew on mine. You can follow one of the wires from the altenator to there. Check it out.

Thanks a lot! I will go check on that!

Check to make sure that all the lights (brake, dome and such) are off. Ask the shop to test for an excessive current drain with the engine and all accessories off. If the mega fuse was blown the battery would not charge and the alternator would test bad. A shorted diode, stuck relay or accessories on all the time will drain the battery.

jeff

I had something similar to that happen to me, it turn out the wires below the battery were fried, and I had to get them all replaced. It cost me about 300 dollars.

My nephew is mechanic i remember him telling me he had same problem on new car. Ended up problem was light staying on somewhere nobody new about. Check out of the way lights on car that you can't see unless you look. Like trunk glove box underhood. Something is just draining the battery if alternator is good

Leave the battery cable off all night and see if it has the juice to turn it over in the morning. If it doesn't, you have a battery problem. If it does, something is still on like a radio, amp, or map light. Any aftermarket accessories?

get your alternator tested for output.