The Lights on my 2001 windstar will not go out. it is the left hand signal and tail light. Has any one seen anything like this before? I have changed all of the bulbs with no result.

Please help.

Keep in mind that all the exterior lamps get a constant 12 positive supply .... its the ground path that gets "switched". ... so all it takes is an erroneous ground.

I'd check the lamp fixtures again.