I just purchased a '99 Expedition.

One thing I've noticed is that the interior lights and running board lights stay on as long as any of the doors are opened, including the tail gate. I can see a dead battery in my future, especially because of the tail gate.

Aside from pulling the fuse from the lights, is there any way to add a timer to them?

 

Do a search on the subject there are some detailed replies. The tailgate you can close the latch, push the latch with a srcew driver all the way in as far as it can go, BUT YOU MUST UNLOCK IT before closing or you may damage it. Another method is putting a switch in the I believe white/purple stripe wire in the harness going to the tailgate. Others say on the dash light switch the dimmer control that clicks when rotated all the way down to the dimest setting turning off the interior lights. My 2001 EB does not do this and I asked a Ford dealer and they knew nothing of such switch. If the dash switch is true I wish some one could post a Ford part number for me.

 

I am also curious if the light duration can be increased when the interior lights are triggered with an unlock command from the remote fob.