Have GMC Yukkon Denali 2005. I recently replaced rear hatch actuator. Actuator is working fine except it locks if I unlock the vehicle and unlocks if I lock vehicle. Please help.

The rear hatch locking is computer contolled .
The BCM also runs diagnostics on the liftgate lock relay control circuit and will set DTC B3825 as current and also send a Class 2 message to the DIC. The DIC will display REPLACE LIFTGATE FUSE to inform the driver that a fault has been detected in the liftgate lock circuit and that the liftgate is not locked. Faults that will set the DTC and cause the DIC to display the message could be any of the following:
• An open ECC fuse
• An open or short to ground in the liftgate lock relay battery positive voltage circuit
• A faulty liftgate lock relay
• An open or short to ground in the liftgate lock relay control circuit
• A short to ground in the liftgate lock actuator lock control circuit
• A faulty BCM

The liftgate lock relay supply and coil sides receive a constant voltage through the battery voltage supply circuit and the ECC fuse. The normally closed contact is connected to ground and the control side is connected to the body control module (BCM). A lock function will occur when a door lock switch activation, keyless entry lock transmission, auto door lock function or a liftgate lock function has been received by the BCM. The BCM will then ground the control side of the liftgate lock relay. This energizes the relay and allows voltage to be applied to the liftgate lock actuator lock control circuit. Since the other side of the liftgate lock actuator is connected to the normally closed contacts of the door unlock relay to ground, the liftgate will lock. When an unlock function occurs the BCM will ground the control side of the unlock relay and the rear doors and liftgate will unlock.
The power door lock system consists of the following components:
• The driver door module (DDM)
• The passenger door module (PDM)
• The body control module (BCM)
• The driver information center (DIC)
• The rear door lock switch
• The door lock relay
• The door unlock relay
• The liftgate lock relay--utility vehicles with liftgate only
• The reversible door lock actuators in each of the doors and liftgate
• LOCKS 20A fuse (rear lock/unlock relay supply voltage)
• ECC 10A fuse (liftgate lock relay supply voltage)

If i were to guess i would say you mite need a new lock actuator , but i don't guess . You could take the hatch inside panel off an check for B+ voltage for the lock actuation as someone pushes the switch . Or have it checked for codes .

Check the ground to the actuator, if that is ok replace the actuator.

I own a 04 durango and the door lock actuator froze up internally and I could not open the rear hatch. After hours of research on my computer nothing seemed to fix the problem. I eventually figured it out myself. You must pull the screws out of the molding on the inside of the rear door. You can now pull the molding toward you and look down at the actuator and latch. You can pull on the molding quite a bit if necessary. I never broke mine and I was pretty agressive with it. Now, on top of the whole mechanism is the lock actuator. There should be a white plastic lever sticking out towards the driver side. If you can slide it from back to forward "forward is front of vehicle", the lock should be working. If not your door is not unlocking. My durango had 3 Torx screws on top of the actuator. Remove them. This will take the actuator off of the latch. Now that the actuator is not binding or holding the lock from moving, again try to move the white plastic lever towards front of vehicle. It should click and you should be able to open the door.

are you talking about the actuator that unlocks the hatch?

Sorry, I don't have the data now..... but.Some hatches have a manual release on the inside. There might be a small plate near the door center that you can remove and open the hatch with a screwdriver.

but...I'm not sure tho about your car.

It should still be able to be locked and unlocked by the key, but if you mean locking by the remote, then the actuator is bad. These can be purchased from a dealership, parts yard, or I prefer to buy from Ebay. If you go to Ebay, just look up 2006 Yukon actuator. You may get a better price also.

wiring connections or lock latch frozen --to manually bypass latch or to unlock rear hatch -- in the bottom of door panel is a round access hole remove cover just clipped into place using a flashlight and a screw driver about 3 inches in on bottom is the lock latch and window lock latch connections if u pull back on the inner latch u will unlock the hatch which will allow u to open it[ when opened check the wiring connections for corrosion or damage if good ] now u can remove the whole hatch panel and check the latches and actuator the actuator and latches,and rod clips sometimes need to be lubed or sometimes the clips break or disconnect clips can be purchased at any auto store panel is clipped into place carefully pry from a corner and using a screw driver or panel tool pry straight back till panel clip pops replacement of panel put clips in place and push in panel

First, on the rear hatch, there is an actuator. On FX, when you close the trunk, it kind of **** the hatch closed all the way. When you press lock on the remote, this same actuator locks it as well.
Now,
1) when you unlock the car from the inside, go back there and press the button to open the hatch door manually, do you here any noises?
2) Close all doors, go back close to the hatch button and using the remote , lock the car and then unlock the car. you should hear a sound from the actuator locking and unlocking the lock on the rear hatch!

If you don't hear this, your actuator is inop.
Next step would be to check the fuses inside the car, on the left bottom driver side, and outside on the battery compartment.
It might be just a fuse.
If all fuses check ok, your actuator is most likely gone! Not ea expensive fix, just time consuming!

NOW, if you can hear the noises, then something is either broken inside the actuator or one of the cables is loose!
Hope that helps.
Also, what year and miles on your fx?

Check battery voltage. if above 13.7 volts move to rear lock actuator and measure battery voltage at actuator if above 13.6
replace actuator if below specs. check grounds and alternator out put as follows, alternator output 13.7 to 14.25 volts. key off battery volts should be 12.90 + - 3/10 of a volt and about the same voltage at the actuator. let me know. kindest regards Bill

how do you removed the interior cover? for the rear door actuator?