2009 yukon denali chime door start to lock and unlock every time i hit a bump, lift gate open light come on

SOURCE: lift gate wont open with remote

I spend the next 10 minutes alternating between randomly hitting the FOB’s lock and unlock buttons, until I give up in a garage-filling string of expletives as I realize my kayak and I are SOL. Luckily, I did have a friend and an incredibly helpful REI employee there, whom all pitched in and managed to jam the kayak into the Suburban through the side door. I love my Suburban for reasons like this, though I’m slowly starting to hate GMC. More on this to come.
Here’s the Suburban with kayak inside and the lift gate panel on the floor. If you have a Suburban / Tahoe / Yukon in the same situation where your lift gate won’t open, the only way to get it open is to pry the lift gate panel just enough to access the locking mechanism. Take a long flat head screwdriver, slip it into the top section of the panel and start pulling away. The panel is made of a flexible plastic that will bend a fair amount, so don’t be afraid to put a bit of elbow into it. Once you see the locking mechanism, you’ll want to grip the back side that moves and twist counter-clockwise until the door pops open. Once you’ve done this, call GM customer service and tell them that their engineers should be fired for not having a manual release. If there is an accident / fire up front, wouldn’t you like it if your kids could escape out the back? Yeah, me too.
If you’re lucky enough that you can open your door (or maybe it doesn’t lock to begin with), then it’s a little easier to pull off the panel. First, take a socket wrench (9mm, I think) and remove the bolt under the leather handle on the inside of the door (the one you pull down on when your lift gate is up). After that, insert a flat head into the space between the panel and the door and pry open. There will be around 4 or 5 contact points to disconnect.
The two last things that stand in your way are plastic hinges that hold the panel to the door frame. With the lift gate open, push the panel toward the car, then spin it an entire half-circle around the hinge in the picture. After that, the panel should pull right out. Now the locking mechanism should be nicely exposed.
Here we see the lift gate handle at the bottom, which is connected by a tension wire to the locking mechanism. Pulling on the handle causes the wire at the top to retract toward the right, turning the locking mechanism counter-clockwise.
However, pulling the handle does nothing when the mechanism is in the locked position, because it doesn’t engage the other tension wire / tailgate release - it just simply moves by itself. When the mechanism is unlocked, pulling on the handle will engage the release mechanism and pop open the door… when the locking mechanism is working, that is.
Here is a properly unlocked door: notice that the black plastic piece (on top of the copper) is slid all the way to the right. You can see that if you rotate the lower copper piece, that it will force the black plastic piece to turn, thus engaging the door release.
Here is why your Suburban tailgate won’t unlock. I’ve just pressed the unlock button on my key FOB and you can see that the black plastic piece has NOT slid over to the right. This means that the door is still LOCKED as far as the mechanism is concerned. No amount of yanking on the handle will open the lift gate at this point.
Zooming in for a close-up, you can really see where the problem is. Gear heads will realize this is a major problem for all sorts of reasons. First, if your door lock actuator is banging against this metal part every time you unlock your door, it will wear out the part extremely fast and you’ve got yourself a busted door. Second, even if you replace your actuator, you’ll just bust it again if it keeps ramming this part. Most importantly, the question is how this is happening to begin with? My Suburban was working fine until I put in a factory replacement handle.
My opinion is that the factory GM replacement was defective and not built to spec, because the tensioner was now pulling a few millimeters more than it should have, which resulted in my lift gate not closing or unlocking. While millimeters might not mean anything to some cheap factory in China or Mexico, it means a whole lot of difference to the Joe Schmoe who wants to have a car that works. It may also be due to a small and very important spring that resets the lock back into place.
I’ve read a whole ton of reports about Suburban lift gates, along with Tahoes, Yukons and other GM cars failing and drivers stuck with unlockable doors. I believe this type of careless “few millimeters off isn’t important” BS is likely to blame. That’s why some people may have locks that work only half the time, or some work after their actuators are replaced, but fail soon afterward. My two-cent opinion - back to fixing cars.
So what we need to do, is make some space for that locking (technically, “unlock”) mechanism to engage fully. On my Suburban, this meant giving the metal tensioner just a little more slack - 2mm would be all I need.
First, I pushed the handle wire mechanism over to the right and then pulled out the metal ball and wire. After that, I pinched the blue wire cap and pushed it out of the metal holder.
You can now see that there is a lot of visible space between the locking mechanism and the metal. Pressing lock and unlock on my key FOB easily moved the unit back and forth successfully, so I knew it wasn’t a problem with the actuator. Now comes the disclaimer part.
DISCLAIMER: Attempt this section at your own risk, you are responsible for your own actions!!! Not seeing a lot of options, I decided I would take a somewhat drastic approach and bend the wire holder closer to the locking mechanism with a pair of pliers. I only needed about 2mm, so I felt this was acceptable without busting the car too much. Needless to say, this is not a graceful fix nor one I really wanted to do, but there appeared to be little other options other than cutting your own tensioner line (adjusting the line would be the most logical method, but I pinching and pulling got me no results) or finding some concrete way of bracing the line closer to the locking mechanism. If you come up with an elegant solution, please let me know.
Phew, finally - the fixed tailgate lock! You can see there is just enough room for the mechanism to engage and that the handle tension wire is snugly seated into its new home. I tested the lock about 100 times to be sure that everything was working as it should and I advise you do the same once you get to this point.
Now, simply put the panel back on the same way you took it off (don’t forget to screw the bolt back into the handle) and you’re done. Have a beer and go pat yourself on the back.
If this blog post has helped at all, I’d appreciate if you left a comment to share you experiences so others in the same situation can hear what you did. Thanks.

SOURCE: HOW TO OPEN LIFT GATE OF 2005 YUKON XL

have you had someone try the unlock while you listen at the hatch to see if you hear the solenoid working?
My guess is your going to have to remove the rear hatch panel to gain access

SOURCE: My yukon 2006 lift gate

Hi,

I have had several of the Tahoes with the same issue... the fault is with the lock/unlock actuator inside the rear door. if it fails and doesn't move the release on the latch... the door doesn't operate properly.What you will need to do is to remove the upper trim panel by pulling it off the door towards the front of the vehicle (it's held in by clips) and then pry/pull back the lower to access the actuator and move the arm and release the door.after you get it open and replace the lock actuator for the liftgate. This should take care of your issue.

Let me know,if needed further assistance.

Hope i helped you.

Thanks for using ' Fixya ' and have a nice day!!