Trailblazer remote/alarm issue

[sunliner]

Have an 06 Trailblazer LS that is driven by my son. It has what I'm sure is an aftermarket remote door unlock system (vehicle has a key slot on drivers door, and I found the module for the remote and it's definitely not GM). The thing has always acted sketchy off and on, but for the last month or two, the remotes don't lock /unlock the doors at all. So now, when he parks the truck, son uses the button on the door to lock the truck, then uses his key to unlock. Problem is , 99.9% of the time, this triggers the alarm which is getting embarrassing. Almost thought about disconnecting the horn, but not a good idea. So here's the initial questions:
1. can the alarm system be disabled ? (pretty sure its' a hard 'no' but I gotta ask)
2. given that the door lock remote is aftermarket, does the lift gate module come into play in any of this? I've heard if the LGM is bad, it can lead to all sorts of electrical weirdness in our trucks.

 

[coolasice]

The door might have a bad switch in the lock as it is supposed to disable the factory alarm when the key is used. If it is an aftermarket alarm, the best thing would be to disable it completely or replace it with a newer unit.

 

[TollKeeper]

Remove the aftermarket kit, and check the RPO and see if it has a factory installed RKE. It should. I have not seen a GMT360 that didnt. If it does, its just a matter of getting some FOB's from ebay or something, and programming them, which is really simple.

 

[Chickenhawk]

As far as the key setting off the alarm, this is common. Cool as ice is correct. You can replace the door lock actuator, and this will fix it. It is a fiddly repair, but straightforward.

 

[sunliner]

As far as the key setting off the alarm, this is common. Cool as ice is correct. You can replace the door lock actuator, and this will fix it. It is a fiddly repair, but straightforward.

I did not see the AU0 code on the RPO sticker so I don't think this thing ever had factory RKE.
will give the actuator r/r a try, sounds like the most likely culprit. much thanks to everyone who replied

 

[aaserv]

Mine has an aftermarket alarm system. It appears to totally contained in the compartment under the steering wheel. Mine has 2 or 3 little boxes spliced in and wires leading to a horn under the hood. I havent done it yet but I plan on just taking it all out wire by wire and splicing the original wires back together. I don't have a key fob either and never had 1 so i have to get that done as there is no way to lock the back door without it that Im aware of.