I have been reading the forum for a couple hours now and I am not finding any similar problems/solutions as to why my door ajar light is on with all doors/trunk closed and ignition off on my 1988 GT.
Back story: A few years ago I took the bulb out of my trunk light because the switch went bad causing the light to stay on all the time and killing my battery. Well, fast forward to today and I'm finally getting around to all the little things on my car that I want to make right after getting the mechanical problems squared away.
Today I installed my new fierostore trunk switch and new light bulb. Bulb works great and when I close the switch manually the light goes off, however when I close the switch the ajar light illuminates on the dash. Oddly enough when I take the bulb out the ajar light goes off which makes no since to me because they are seperate circuits and really the ajar circuit isn't supposed to have power with ignition not in run according to the diagram.
I took the new fierostore trunk switch out and put in an old one that works and I no longer have the issue. I contacted the Fierostore and they are sending me another switch. It must be defective and allowing the light voltage over to the ajar circuit?