Hey guys (and girls)-
Vehicle info:
2005 GMC Envoy XL (4.2 I6 with 72k miles)
So the issue is that the key fobs will stop working intermittently (Both of them, not a battery issue). When this happens, I can’t get the rear hatch open unless I pop it the manual way via screwdriver.
So after googling the issue, it looks like it could be the liftgate module or rear hatch module which
controls the rear hatch and the key fobs. I checked the fuses under the driver side rear middle seat and all
is good there. Some also mentioned that it could be the wiring in the rear hatch door. What stups me is that
this issue happens on and off. Yesterday they didn’t work, today they did. Do modules “slowly” start to go
or is this more of a symptom of a loose connection. Either way how do I fix and what do I do? Much help needed
as I don’t want to pay mucho money to a shop to “digg” for the answer. Much thanks in advance!
This is confusing could use more detail. Do the other door locks work? Does pushing the driver’s door unlock button twice, in fairly quick succession, unlock the hatch properly? I can’t see how a screwdriver could be used without significant damage unless it was unlocked and partially unlatched. Can you explain how you pop it open with a screwdriver?
The trouble appears to be due to a faulty connection somewhere, possibly a power connection. Having a test light probe and good wiring diagram should help you pin down wher the trouble is. Since it is intermittent it may be more difficult to find. Tapping on suspected trouble areas may help find the trouble also by making it fail or work.
Yes, the other door locks work fine. There is a “manual” way to open the hatch via a hole in thee door (inside the truck - you pop the cap of and push a screwdriver in and it opens- its made for this purpose).
You can push unlock as many times as you want and the rear hatch will not unlock (when the issue is occurring). If the whole system works as it should, then yes, usually pressing unlock twice does open all doors including hatch. Hope this helps?
OK, so then it has nothing at all to do with the fobs if the hard wired switch doesn’t work either. On mine, you push the fob or door switch unlock once to unlock the driver’s door, twice to unlock all doors. There is no separate button for the rear door or window.
I had no idea there was a mechanical latch release, I haven’t had to resort to that on mine yet. Good to know.
I have a schematic for the 2004 year model that may be helpful. I can’t get at it until later. However, the rear door has a wire bundle near the top that flexes each time the door is opened or closed. Due to the intermittant nature of the problem, this is the first thing I would suspect. The wires gradually break as they get flexed repeatedly and the failures become more frequent until it finally fails. Happens in door harnesses fairly often. You could remove the interior trim panel and see if the unlock solenoid is getting a signal when commanded or if the latch mechanism is simply gummed up and too difficult for the solenoid to actuate.
It’s weird. See the issue I am having isn’t uncommon (well google research showed me a lot of possible leads). Apparently the rear hatch module does go bad more often than one would think. It’s job is to control the hatch and the key fobs. When the system is down… you can use the power door locks (drivers side door) to lock ALL locks in the truck. However when you unlock them, it will not unlock the hatch.
When the issue occurs… the key fob will not work on any lock. You can tell there is no communication via the fob and truck. No sound/clicking/nada.
It showed 3 possible fixes… I would need a new module, the rear hatch module fuse blew (it didn’t), or a loose wire connection in the rear hatch. I couldn’t seem to find a story though similar to mine where it happens on and off. Most seem to stop working…and not work again until fixed.
I am by no means an electrical expert, but don’t mind attempting to fix it if I know where to start 
Hope this helps. If not… let me know and I’ll attempt better detail. Thanks to all for the input so far.
To clarify, the lock switch in the door does work and hasn’t stopped working. When the fobs and rear gate have their issue, the door lock switch (located in the drivers side door) continue to work
I have the same problem with my 2005 Envoy XL. The rear hatch tends to not open in cold, wet weather. For example, I live in Cleveland and the rear hatch has not worked (meaning the hatch doesn’t open, nor does the window on the hatch, nor does the rear wiper, nor does the rear wiper washer.) However, in the summer, the hatch will open. It’s not guaranteed, but the likelihood of the hatch (and other parts) working in warmer dryer weather is greater than the likelihood of it working in wet, cold weather.
The key fobs, on the other hand, don’t work all the time either. (Both fobs) work sometimes and sometimes they don’t. When they work, the fobs will unlock, lock, and panic the vehicle. However, when they don’t work, it is like a fob was never provided. The key has to be manually inserted in the driver side door lock and then the doors must be unlocked from the driver door.
Very strange issue. The weather factor makes me think that it is a wiring issue. HOWEVER, the fob issue and the rear door issue are separate, meaning sometimes the rear hatch opens and the fob doesn’t work, sometimes the fob works and the rear hatch doesn’t, sometimes both work, sometimes neither. GM dealer (on multiple occasions) has told me they have no idea what is wrong. Because it is such a tempermental issue, it’s hard to show the dealer. Any help would be appreciated.