Ford F150 - door ajar

Hello All, I am having a problem with my door ajar light. I will fill everyone in on what is happening, when my door is open of course the door ajar light and overhead light is on, but when I close the door both lights stay on. After a few minute or so (but not always) I hear a click sound and both lights go out, not to come back on until I open the door again. This does not always happen,(but most of the time it does) sometimes it works great with no error though. I assume there is a button or sensor inside the door or behind the front quarter panel but I am not sure and would love some direction, I know that other vehicles have a little nub that is pushed when door is closed but with the door arm that the f-150 has I am really not sure where to go/look. Thanks in advance for any help, I am hoping that someone else has already experienced this before me, this way I don't have to dive into the door only to find out its something else. Thanks again for any future replies.

It would really help to know what YEAR the truck is.

That problem is not unusual on early models. Try spraying a liberal amount of WD-40 into the door latches in both doors and open and close the door a few times. The switch is in the latch on many models and tends to stick.

Sorry Steve83 for not writing the year, the truck is a 98 f-150 XL. RkyMtnHi, I have tried the W-D 40 but it is still doing it, I am wondering if there is a small part that can be easily replaced. I was not 100% sure about your post, did you say that the sensor was in the door itself? Thanks a bunch for the help and I hope to hear back from you guys again. LONG LIVE THE F-150