I had the same problem.
I am 99% sure that it is your (GEM) Generic Electronic Module.
It is basic Ford system item but they are all programed different for different models and years.
Remove the panel under the steering wheel column.
The module is to your right around the radio area. (Between the radio and the steering wheel).
Easy to find with 2 plugs on it. It will have the numbers (pretty large print) on a sicker directly on the module.
F48F-14B205-AK or F48F-14B205-AG are the numbers you can use. You will have one of these two numbers in your Windstar. I really think the AK or AG will interchange.
Go to U-pull-it salvage yard and pull one for about $10.00.
1995 and 1996 model years only interchange and you can use a AK or AG as long as you don't have air lift suspension.
The GEM controls your interior lights, windows, wipers, washers and the list goes on.
The interior light on an 87 cabriolet is located above the mirror just above the windshield.
the same thing happens to mine........just turn the interior light switch of......it works
Sounds like normal operations / behavior.
One thing that will cause this is when a door-ajar warning goes without fixing.My Windstar rear hatch showed as ajar for quite some time - after a period, this caused the interior lights to be disabled.Flooding the hatch latch mechanisms with spray lubricant, i.e., WD-40, cleared the false ajar warning, and the interior lights automatically starting working again.See "Related Questions" below for more
check the fuses
Heat cut the windshield out, just make sure not to damage the brake lights, and the windshield wiper, fit the new glass to the back, and weld it on the inside after removing the fabrication, put the fabrication back on, make sure the brake lights and windshield wiper work, and if they do, you're good, if they don't, visit an inspection shop, they'll hook ya up.
In the upper console above the windshield where the two lights are located there is a rocker switch giving the option of On, Off and with Doors.
In the center of the dash on the left side is a timer relay. it is probably bad, causing the delay part of the lights to not work.
http://wiki.answers.com/Q/Why_dont_power_windows_sunroof_wipers_and_interior_lights_dont_work"
To turn off all the interior lights, move the dimmer switch "scroll wheel" all the way to the bottom - you'll feel it hit an indent.If you're having problems with the interior lights staying on with all the doors closed, it's likely to be the very common false door ajar warning problem.See "Related Questions" below for more
The Windstar has a position on the light dimmer scroll-wheel that turns the interior lights off, even with the doors open. Great for at the picnic, tailgate party, cleaning the car, etc, to keep from killing the battery. Make sure the dimmer switch scroll wheel is not all the way up (or is all the way down?) Also - If you have a malfunctioning "door ajar" switch, after some time, the Windstar will deactivate the interior lights. Fix the door ajar warning and the lights will resume normal functions. See "Related Questions" below for more on stuck 'door ajar' sensors
There is a spot, all the way down, on the dimmer 'scroll-wheel' type dial that will disable the interior lightsWhen I had one of those common problems with the false 'door ajar' situations, my 2001 SEL deactivated the interior lights. Once I resolved the false signals coming from the liftgate, the interior lights automatically started behaving normally all by themselves.See "Related Questions" below for more