Tailgate won't latch shut

How to Replace Tailgate Handle & Bezel 88-00 GMC Sierra K1500 - YouTube
How to Replace Tailgate Latch Rods 88-00 GMC Sierra K1500 - YouTube

you have to make sure the strikers are lined up to the latch. The latches get dirt in them and dont move easily. You may have to remove the latches and clean them and grease them up make sure the action is working. There is a spring on the latch if it is broken you will have to replace the latch. Make sure as you before you shut the tailgate the the latches on the tailgate are open and not latched closed. You can put a screw driver in the latch and pull the handle and that should release the latch in the position ready to accept the striker when you close it Next make sure the plastic clip retainers are not broken on the handle

Tailgate/trunk latch will not engage so the tailgate just bounces won't close - is there something I can do to fix this on my own?

If you remove the ring around the handle you will get a better view of the two rods that connect the handle to the outter latches.The ring just snaps in.I think a flat head screw driver from the bottom works the best.Once you have access to the rods you can push the inward twords each other to pop the gate.If the are broken out twords the tail lights then a thin flat head in the gap betwen the tail lights and tail gate should be able to push the spring loaded latches in to pop the gate,but you may need to borrow a extra set of hands.Well hope this helps.

There are two Possibilites with this issue ... Either the latches are bound or rusted and can be lubricated with lithium grease after cleaning or the plastic retaining clips may have broken inside your tailgate. To locate these, remove the three bolts holding in the latch assembly and inspect the clips attached to the two control rods that will latch/release your tailgate. I have found spraying white litium grease every three months into the latches of my tailgate has eliminated the same problem on my truck.

Sounds like you have a bar disconnected inside the hatch. You may also need a latch itself. Does it lock and unlock? If it does, most likely a bar off issue. Will be a pain to get the cover off with the door closed, but you will need to remove it to inspect.

Common problem on these vehicles. Keep it simple and bullet proof by just loosing the original arrangement and screwing in a manual latch on each side. A couple of gate latches are cheap and work forever. Not pretty but functional.
If you find anything at a junk yard it'll cost plenty and will be bound to fail like yours already has.

look under the latch and see if you see a metal rod. if you do, pull the rod and it should open.

Which Brake line are we Talking about. The one from the Master Cylinder or one from a Caliper on??????????

I have a 2002 Chevy 3500 and the same thing happened to me. It turns out the latching mechanism on the left side would not release when I pulled on the latch handle. I stuck a small screwdriver in there to release the latch handle (as I pulled on the latch handle) and it popped open. I then squirted some WD-40 on that latch mechanism because it was hung up. I didn't have any problems after that.