Ok, for starters, yes I replaced both the drivers and passengers side door jamb switches, yes I know for sure the issue is on the driver side, and yes, multiple times I've WD-40'd and slammed the **** out of all 4 doors.

My door ajar light comes on whenever I hit a bump or even lightly press the drivers door from the inside. Slamming it shut, specifically rolling down my window and shutting it hard with my arm outside does the trick, but if I hit a bump or press the door even lightly, the light is back on. Clearly, something is loose, but I have zero clue where to begin to fix it. Please help me get an inside lamp back in my truck (I've ripped it out for now), I work nights and it's a pain in the *** to use a flashlight every time I need to grab my things. Thanks everyone!

 

Welcome to the forum

The Door switches are GROUNDS when door is opened, when GEM(cab computer) sees any door switch is grounded it turns on the door ajar light and dome light

So for now unplug the 2 wire connector on the drivers door switch and see if problem stops OR is still there, because it could be REAR door on drivers side
If problem goes away then you will know its the drivers door setup, so if switch is new then it could be latch is worn out inside or door striker needs to be adjusted

The WD 40 thing
The door switches on driver or passenger door are located at the bottom of the latch, so any water that gets in will wash down dirt/debris to those switches, this can cause switch to short or "ground out":even when door is closed
So spraying WD 40 into the latch "might" clean out the switch so it could unGround with door closed
Replacing the switch would take that off the table, the WD 40 is not to lube the latch, just to clean out the dirty switch

The wire from switch to GEM can also get a short, so an intermittent ground, this doesn't sound like your issue, since you can push on door to get switch to Ground

The strikers on doors are adjustable, this can hold the door closed more, so no "wiggle room"
Slamming the doors won't help solve this problem...................but can make you feel better, lol, so slam away

 

Thank you for the answer and the welcome Ron
I'm definitely thinking something is loose with the latch, as the door tends to move out slightly when I press on it and the light turns on. I'll look into what I can adjust with that, along with the rear door. In terms of the "slamming" part, I was merely referring to what I've seen in dozens of threads, where the solution was always "spray wd-40 and slam", likely to loosen debris as you said. I just wanted to clarify from the getgo that isn't my issue.

​​​​​Here is a link of the issue in action. I'm nearly certain something isn't right with the alignment.

https://youtu.be/GWq6-hP-w18