Driver Door lock doesnt unlock with remote

My gf has an 03 tacoma that came with manual locks and windows. She has an aftermarket alarm that allows her to unlock the doors from the remote but when she unlocks the doors the driver door doesn't unlock. When she presses the lock button ,however, all the doors lock. I've been creeping the internet and from what I've been reading people are saying it could be the actuator.
My question are:
after I take the door panel off where is the door lock actuator?
what does it look like?
how do i test it if that is the problem?
if it is the problem just replace?
any other ideas on troubleshooting the problem would help alot

 

I have one suggestion that can help you with diagnosing. WHile sitting in the truck with the doors locked, use the switch on the armrest to try and unlock the doors and see what happens.
I did read a couple of other guys had similar problems, and there was a linkage piece bent inside the door panel that caused it and it was easily repairable.

 

From what you described, it sounds like someone installed aftermarket door lock actuators. Installing these actuators requires that you attach the door lock actuator to the lock rod; this is usually done with a brass connector with two set screws. It is probably either one of these set screws loosened over time (which is not uncommon if the installer didn't use thread lock on them) or there's something wrong with the actuator itself. The only way to troubleshoot is to pull the door panel and poke around to see what the issue is.

I included a picture of a typical aftermarket door lock actuator install so you can see what you should be looking for.

 

bicklebok - the truck didn't have auto locks when it came with truck so there is no autolock button inside the car
Rusty - that's what i thought about the aftermarket actuators. In the picture the black piece is the actuator and the screws you were talking about are highlighted?
if anyone has any other ideas feel free

 

Yup! You've got it!

 

if its the actuator like that, maybe replace it yourself..

http://www.topgearautosport.com/part/A101Q8QR176/Universal_Power_Door_Lock_Actuator.html