On mine, if there is any play in the bottom, that stupid door ajar light comes on. I need to make sure to push the door closed firmly from the bottom to get it latched right.
It does latch nice and tight though. If yours has any play, its not shut right.
Also, the striker on the door sill, the bolts can become a b*****. I stripped one, had to pay $8 for a 4 pack from the dealer.
Adjustment is easy, but mark its location first, if you mess it up, it can take a while to get it to latch right. If its off by a bit in the wrong direction, it can make your latch stick and hence you might have a very hard time to open your door. I over adjusted mine, and had a very hard time to open the door to readjust it, it felt like the door was going to rip off the truck.
I think it was a t35 or t37 or was that a t40 torx bit for the latch?