Do you know Where and how would I fix this?

 

Need a real wiring diagram, that shows how things are actually supposed to work. Factory service manual is about the ONLY thing that will have that. It may also have troubleshooting steps to find out what exactly the problem is, so you aren't just tossing parts at it.

 

My door locks sometimes stop working and sometimes they work all of a sudden. When I'm in the car and press the lock or unlock function I do hear a very faint noise, almost like a low battery type of noise. I added a extra alarm on my car a while ago but it's a cheap brand and I'm not sure if that matters or if it's affecting it.

 

If the add-on alarm is hooked into the power lock circuit, that is a real possibility.