Lock of the Trunk activates sometimes

Hey all, I have a really frustrating issue with my 2003 Chevy Trailblazer, basically the trunk closes fine but what happens is that sometimes when I activate my alarm all the doors in the car lock but the trunk doesn't lock. So I have keep pressing the unlock/lock button a couple of times until I hear the trunk finally lock.

I thought it was the alarm failing me so I went ahead and had it switched. The people that switched the alarm said that there was nothing wrong with the main wire that runs through the entire car to lock up the trunk. They also mentioned that I had to make sure that I slam the trunk door closed so that the alarm is able to lock the trunk. Unfortunately the problem still persists, I went to my mechanic and explained everything to him and he said that he was going to move the hinge where the trunk door latches onto a bit more forward so that the trunk would have a higher chance of locking when I press the lock button on my alarm. He also told me he tried it numerous times and it worked every time.

So once I got home and I tried it myself on my second try it fails. :(

This is what I do to check the trunk. I just hit the lock button and I check to see if its open and I repeat the process until it happens. Ive tried this to other cars and they work every time except for my car.

Has this ever happened to anyone else before? I'm just wondering what else could be done because I just want to trust my car when I run out of the car and activate my alarm without the need to check it.

Is there any way to check any of these issues like maybe the lock housing is messed up ? or do I need a new hinge where the lock makes contact to? or should i personally push that hinge more forward than what my mechanic initially did?

The other day it started raining really hard as I got close to my job and when I hit the lock button the trunk didn't lock so I was out there getting soaked in the rain while correcting the issue. This is getting so annoying I really hope someone out here can help me :(

There is no quick answer here, the lock mechanism should be gotten into and inspected for any binding, that is step one.

Thanks for the response :D

Was my mechanic suppose to check for those bindings though? Because it was yesterday when he checked the trunk (he didn't charge me for it though). All he did was move the hinge that is attached on my car closer to the back (so the hinge has a better chance of getting latched by the trunk when its closed) Is there a person better than a mechanic that should be checking this issue? Could I do this myself? Wish I knew more about cars :(

Thanks for the response :D

Was my mechanic suppose to check for those bindings though? Because it was yesterday when he checked the trunk (he didn't charge me for it though). All he did was move the hinge that is attached on my car closer to the back (so the hinge has a better chance of getting latched by the trunk when its closed) Is there a person better than a mechanic that should be checking this issue? Could I do this myself? Wish I knew more about cars :(

My Trailblazer don't have a trunk. :dunno:

So what is it called then ? The back door?

Come on guys, tailgate. The interior trim panel should be removed and the lock/linkage checked for binding, where you are there are no rust isues like here in upstate NY, but this is the first thing to check. A body shop may be a better bet here.

My tailgate has a window that never locks but if i open it when the tb is locked the horn will sound till i get a key in the ignition