1998 ford windstar electrical problem

My 1998 ford windstar is having sudden problems with the door open idicator. Although all doors are properly closed, the indicator light comes on and all the interior lights stay lit. After several minutes they time out but when I put the van in park and turn off the ignition, the interior lights stay lit. They do not time out. They are draining out the battery. Any ideas as to where I should start looking to find the problem? Check all your door switches. Expecially on the back gate and the slider, they go bad very often. Spray some penetrating oil inside each door latch. Use it liberally. Open and close each door a few times and the light will go out. The door that makes the light go out is your problem switch. By the way, the switches are on the latch inside the door trim. Good luck. Thanks to Way2old and broughy84 for the advice. The problem is now fixed!!

The doors have electric switches and my husband thought that because my battery was so old (original equipment) the problem might be with the battery. He thought that it was so low that as it was dying it had that effect on the switches. Well, we went out a bought a new battery. He put it in and low and behold the "door open" indicator went out and when I turned off the engine, the lights went out like they should. All is well now in my world. Thanks again!