Went to a meeting last night. Someone came in and told me my dome light was on. I went out, checked the dash switch (it was off). Used the door switch to lock the door, shut it, and the dome light went out.

Five minutes later, another person arrived and told me my dome light was on. I went out, put the key in the ignition and turned it to run, then pulled the key out, locked the door and shut it. Dome light went out. As I walked back to the building, I looked back and......... it was on. I checked both doors and they were fully closed.

I repeated the key/ignition/lock sequence a second time, and got the same result..... 10-15 seconds later, the dome light just came back on.

Third time was the charm.... it stayed off. At least for several minutes before the cold drove me back inside. It was off when I came back out 2 hours later.

Door switch? Computer malfunction? Aliens?

 

What year Ranger?

The Door Ajar light would also be on if its a 1995 and up Ranger, if it was a door switch malfunction, assuming door ajar light works, of course

If 1995 to 2003 there should be a Battery Saver relay that will cut power to the dome light after 30-45minutes of key off

Does the Dimmer wheel switch work, 1995 and up?
To turn on and off the dome light

 

2009. The lamp in the door ajar indicator works. Dimmer switch turns it on and off just fine.

 

2009 thats full DIGITAL time, lol

Unfortunately its all operated in the SJB(smart junction box) behind passenger kick panel
SJB has no serviceable parts inside

I have the diagram below

SJB was known to get corroded connections in the large wiring connectors, you can remove those and have a look, clean them up and see if that fixes the issue
But if it was a door switch the door ajar light would activate, so its not a door switch