2005 Mercury Mariner Premier
 

I have a 2005 Mercury Mariner with 119,000 miles. It has started to have problems with the automatic lighting and the alarm system. The alarm goes off at random times when no one is near it, although it never happens if I leave the doors unlocked. I thought maybe it was some kind of electrical interference. Tonight the interior lights won't shut off. This happened once before, but after monkeying around with it for awhile, they finally turned off. Tonight nothing seems to help. They would turn off after a little while, but turn right back on. The readout below the speedometer says passenger door ajar. I checked all he doors and the hatch, opening and re-closing them to be sure they were shut tight. Now the interior lights won't turn off at all.. I tried setting the headlight switch to "off", but it didn't help. Maybe a bad door sensor? Update: After posting this, I looked out at the vehicle and the lights had finally turned off. It doesn't usually take anywhere near that long. This looks to me like potential expensive trouble.