rear hatch not locking

[rews2]

My Tahoe is relatively new to me and found out last night the rear hatch isn't locking using remote or lock switch on door. Nothing was stolen but that is how I found out it doesn't lock I was loading stuff in.
The lip of the hatch where the latch looks like it was opened against something or was backed into something when it was open. What should I be looking for? Is it a cable driven system or something else? Oh, its a 2005

 

[MO Viet Vet]

If locks with a key, you did not say one way or another, then is likely the lock actuator. Open up the cover and make sure is plugged in and that it has proper power and ground when told to lock by the switch or fob.

 

[rews2]

There is no lock cylinder on the hatch itself.

 

[MO Viet Vet]

Ok, then look at the actuator and post results. The damage area you talk about could be a problem though but only if it impedes the movement to latch it. Do you hear anything and still not locking or no noise at all?

 

[rews2]

I can hear the actuator fire but can't tell if its the rear door or lift gate I'm wrapping up another project and will pull the cover off and check it out. I'll update once I can see it.

 

[rews2]

Finally got to it. Pulled the panels to access actuator. I can manually lock and unlock the lift gate but remote will not do either. The actuator feels like it is firing but linkage does not move I threw a quick light on the wiring harness and it is getting power. Light flashes for lock mode but does not one lock mode. Any ideas? Actuator?

 

[MO Viet Vet]

Ok. The linkage at the actuator needs to be unhooked and then watch if actuator has full travel when you tell it to move. Check the linkage for any binding. You have more power to move linkage than the actuator does. If linkage is moving very freely and the actuator does not move fully then the actuator is the problem. If the linkage is unhooked the actuator may move fully but not with linkage attached resistance and then still need the actuator. Need to make sure your "damage" you talked about is not coming in to pay here but sounds like it is not.

 

[rews2]

I can feel the actuator firing when I hit the remote. Maybe something inside actuator is busted. I'm assuming the internals are plastic.

 

[rews2]

Okay I'll give that a shot.

 

[rews2]

I have a stupid question. The actuator and linkage both have arrows that line up, should they line up when locked or unlocked?

 

[rockenthebowtie]

schematic

So when you say the test light doesn't light up when you hit unlock what circuit are you putting the test light on, as you can see on the diagram you would need to put it on the tan colored circuit for unlock, also do the rear door locks operate normal (lock & unlock)?, now if you getting power to both the gray and tan colored circuits your going to need a rear hatch lock actuator there not cheap, if the rear door locks do NOT operate also your going to need the lock/unlock realys in the ip fuse block on drivers side of ip, if your not getting power on the tan wire look for a break in the tan wire at the weather boot at the top of the liftgate when you open it, wires tend to break in that area from the opening and closing of the liftgate, sometimes the wire will break inside of the wire insulation so you need to look closely and even tug on the wire to see if the insulation breaks and there you will find you open circuit

 

[rews2]

I checked both circuits and both lock and unlock, are getting power. With my hand not the actuator I can feel movement inside when I hit lock or unlock function on remote. So most likely need new actuator?

 

[rews2]

Yes rear door locks work.

 

[rockenthebowtie]

Yeup, actuator it is, there not cheap,

 

[rews2]

Thanks for your help on this. Looks like I will need to pull the latch to get to screws to remove it. Are there any tips or tricks to replacing it or is it pretty straight forward?

 

[rockenthebowtie]

Well the new actuator comes with new cables also which I've never seen break and it will make it a lot easier to just use the old one, so what you will want to do is remove all 4 cable off the new actuator assy and once you have the mounting bolts off the old one remove the cables from the actuator assy only, just make sure you position them to where you remember which slot they each went into so that when you install the new one, this next part is a little bit tricky. Your going to have to swap out the liftgate window push release button, once you have the actuator out you will see a chrome lock pin on the opposite side of the actuator of the release button its spring loaded so you will need a small punch or even a small pockect screwdriver to push it inward at the same time turning the button assy counter clock wise to the open slots and it should pop right out then reinstall it on the new one turning it clock wise its a little trcky getting it back in you will need to align the button arm in first at somewhat of an angle you'll see what i mean once there, reattach the cables first before mounting actuator and test befor putting trim panels back on, Good luck and may the force be with you

 

[rockenthebowtie]

Almost forgot, yes you are very welcome : )