I have an aftermarket car alarm installed in my car, after GM did some work which involved removing the PCM and some wires on the passenger under panel of the car my factory car alarm is working as well as my aftermarket alarm. I think they might have hooked something back up ????

If I disarm my aftermarket alarm and open the door the facoty car alarm goes off (horn honks)
Also the aftermarket button no longer unlocks the driver side door ( factory alarm is overridng this)

What do I unplug to fix this? and where is it located?

 

I had the same problem. Look in your manual, there's a way to put the car in "programming mode", and from there, you can completely disable the factory alarm. Hope that helps.

 

I dont have the factory keyless entry remotes. Do I need these to do thaT?

 

Can we activate the Factory car Alarm and use the key Fobs too?

Heck I didnt know the cars came with it and it could be programed in the pcm.... can we?