I bought this 93 dakota in august, and the tailgate has always latched, sometimes though if i did not slam it hard enough it would not latch completely and would fall when driving, but when I really slammed it, it closed all the time. So I'm assuming its just a winter problem cuz its been under 32 degrees the last two days and it stopped latching completely no matter how hard I slammed it last night. I souped up the latches with liquid wrench this morning, but still does not lock. The latches wrap around the striker bolts, but they dont seem to lock. I have looked around the internet at other message boards, but there seems to be a lot of opinions, like adjusting the striker bolt, or just straight up replacing the latches.

By latches i mean the u shaped device that when working properly clings on to the striker bolt.

 

I would definately adjust the stricker bolts. I had to do that with one side on mine when I got it. But, if you adjust the stricker bolts and the tailgate no longer lines up with the back of the bed, you have another problem.

 

+1 Also try sticking a screw driver in the lock mechanism and see if it locks up.

 

it could be the linkage in the handle area is not releasing, causing the latch to let go with some force perhaps? open the access panel behind and check the linkages and grease them up, good luck!