2000 marquis electrical problem
 

I have an electrical problem that continually drains my battery. I have replaced the battery twice and have installed new battery cables. Th edealer and another shop cannot find a problem. I have also noticed my headlights and interior lights coming on and going off randomly but not all the time. If I jump start the car it will run but there is no guarantee that it will start after sitting for a day.

improper tires is your problem, trust me.

If you have the keypad entry system, they have been known to cause intermintent interior lights and battery drain, etc. It seems the seal to the keypad degrades, and collect water, causing this issue.

You can troubleshoot this yourself by taking off the door panel, and simply unplugging the keypad.

The other, more expensive cause is the GEM, or LCM modules. These are difficult to troubleshoot, and cost $$$$ to replace.

Let us know how you make out, Bill