Fail in the locked position or unlocked position? Or both?
I had this actuator fail once already and I had to open the door manually. I repaired it and it worked fine for about a year. It's not working again , but this time it won't lock.
My rear passenger door actuator is doing the buzzing thing. I have one on order from EBay. Could that affect the hatch actuator operation?

 

First of all, the buzzing of the actuator shows it's working, but the linkage in the door latch is bound up. This is normal for a WJ because of rusting of the latch mechanism. I've had to replace BOTH my rear door latches because of this. The only way to get lube into the linkage park of the latch is thru the child protection switch opening. I bought both my rear latches from the junkyard for $5 each and had to soak them to free them up enough to use, then lube them with gun oil to make sure they stay working. The dealer wants around $150 each for new ones, then they have to be ordered.

The rear hatch is another matter. You might check for broken wires in the flex bundle at the top of the hatch by the hinges. One thing to watch for is the glass hinges. They will lock up from corrosion and if you get too ambitious trying to open it, the glass will shatter!

 

I ordered the rear door actuator for $75.00 from EBay.
The rear hatch actuators are available through the local parts stores. Made by Dorman they are over a hundred bucks. EBay has them by MOPAR for $60.00, Whats up with that?
I will open the hatch panel today and look for broken wires before ordering. I believe the last time this actuator failed, it just stopped working and made no noise, just like now. I could tell somebody had been in there before to. The plastic membrane was all ripped up.

 

There's supposed to be a black insulator cushion over the plastic film as well. While I had mine off, I cut a hole in it over the hatch lock to correspond with the little access door in the panel. The engineers put that little panel in so you could manually unlock the hatch if you needed to, but forgot to add a hole in the cushion!

I had problems with the hatch latches also. There are 2 of them and one failed to latch resulting in the interior lights flashing on every time you fit a bump! I also got a hatch open chime.