98 2wd ranger 4.0 step side.
ive had a door ajar signal come on randomly for years. how do i fix it?
my dome light is taken out (bought it that way) i suspect it has something to do with this "door ajar" problem..
any quick fixes?

 

Welcome to the forum

There is a door switch at the bottom of the latch in both doors(and 4 switches in a 4 door Ranger)

Its a plunger type switch, when door is open the switch is CLOSED, and this sends a Ground to GEM module, and that turns on door ajar light and Dome light
When door is closed then switch is OPEN, so no Ground to GEM and no door ajar light or dome light

Because of its location at the BOTTOM of the latch, any water and debris will end up in this switch, and that can cause it to stay CLOSED......................
You can try spraying WD40 into the latch and it might clean out the switch so it starts to work again, OPEN when door is closed

You can also remove door panel and unplug the 2 wire connector on the switch, so its always OPEN as far as GEM is concerned(and this will tell you if that switch is the one causing the issue, as door ajar light should go off when switch is unplugged)
OR
You can get new door switch and install it so you can have dome light working when door is open

You can't tell which door switch is the one that's staying CLOSED but odds are its the driver door since it gets used the most

Google: ford ranger door switch replacement

There are a few video to watch to see how it works and how to replace it

99.9% of the time its the switch
0.1% can be a short in the wiring between door and body, where the wire bends every time door is opened and closed, if the wire to GEM is shorted to metal part of door or body then GEM thinks door is always open

 

I had the same problem, sprayed a little WD40 in the latch/lock mechanism and luckily it went away. I hope yours turns out to be something as easy as that.