I've got a 2006 Trailblazer LS with a 4.2l inline 6 motor.

Last night, the security alarm sounded on the vehicle. I went out and checked it but found nothing. However, when I went to
re-lock it, the horn would not sound after pressing the lock button on the FOB twice. Everything was locked, but no horn. I
had a spare FOB so I tried it but same result. I waited for a couple of hours and then it seemed to work.

When I drove it out today though, I noticed as soon as I started it that the open hatch warning light on the panel was lit up.

I thought, ah-ha!, I just didn't have the hatch all the way closed and that's why it didn't want to sound the horn last night. But,
when I went to open the rear hatch, it wouldn't open. So even though the system is saying it's open, it's closed and locked.
I noticed the interior lights were staying on all the time too.

Also, when I use the FOB or when I use the lock/unlock button on the drivers door panel, you can hear the four locks of
the regular doors locking and unlocking but you never hear that sound from the rear hatch mechanism now.

So is there any chance this could just be a fuse? I did some searching on google and found a couple of video's on how to
release the lock mechanism from inside, although I've not tried that yet. Some other websites suggested an "actuator". Others
said it might be the wiring at the hinge. One site mentioned a control module?

Anyway, before I start tearing everything apart, all suggestions as to where to start first and what to check are most welcome.

Thanks all.

 

Just a quick follow-up.

Going by the YouTube video, I popped the round plastic cover off on the inside of the rear hatch (near the bottom, slightly off center) and using the
same screwdriver, engaged the latches (right and left sides) and it released the rear hatch door.


After that, I took a still metal brush and cleaned everything as best I could and hit it with some WD-40.

That seemed to help. It's working again, at least for now.

I can only assume though that this means somewhere down the road, sooner or later, I'll have to replace that actuator. I watched the YouTube video
for that as well, it looks like something I could do.


Thanks all.

 

Okay, spoke too soon. After about 1-2 days, it went right back to the way it was before. In fact, it got to the point where the
"open hatch" light on the dash panel was going off, along with 5-6 "dings". It would do that, then go back off, then do it again
sometimes as many as half a dozen times on a short trip.

Long story short, I ordered an actuator from Amazon and installed it. It's been about 3 days now and everything seems to be
working perfectly again. I used the video I posted above for installation and it went pretty smoothly. The one thing I would point
out is on removing the large interior panel from the rear hatch. Most of it is just "pop off" latches (there's a tool to remove those).
However, there's one "gotcha" connection. I had everything loose but couldn't pull the panel completely off. You have to raise
the rear hatch window. When you do, there's a black plastic pin that has to be removed for the panel to come completely out.

Here's a picture of it:



After that, it lifts right out. Here's a picture of the new actuator, after installation:




Here's a link to the item I bought from Amazon:


I hope this helps someone else. Thanks all.