So I just installed some Polk Audio DXi6500 component speakers for my fronts and after the job was complete, I put my car back together only to later find out my passenger door wasn't locking/unlocking. After thorough investigation i realized it was simply a coincidence. All the wires were reconnected, and the passenger door's lock worked for all the other doors as well. It just failed to lock/unlock electronically. So I pulled the panel off again pulled back the door's plastic sheet unplugged the wires and checked for power, and changes in power when activating the lock/unlock buttons. To do this, get your volt meter and tap into the ends of the wires, push lock or unlock and you should see a direct change in power. Usually from 12 volts to 0, or 0 to 12. If you connect them backwards, there may be a negative (-). But that is all irrelevant, as long as you see movement, that is proof that it is your actuator. If you notice no movement in volts, then you have a much bigger problem. I assume taking off the door panels is well know by now, if not there are plenty of forums that will show you how, so i'm gonna skip that part.
These are the wires to tap into with your volt meter. test them both. They are located inside that plastic sheet in the doors on the bottom right hand side...towards the locking mechanism.

You must remove these three screws to remove the actuator. They are very tight, so i recomend either a impact driver, or a socket wrench. I used a 1/2 socket wrench and a 1/4 socket and the largest phillips screw and it came off without any trouble or stripping. Take your time, go slow and it will treat you right. use the biggest phillips screw driver you have to avoid damage to the screw.
there is a 10mm bolt on the door underneath the actuator that holds the window guide, I recommend removing that to give you more room to take out the actuator as it is burried inside the door. Also, before removing the actuator, you must disconnect the cable that comes from the ouside door handle. You kinda have to work blindly here, but you can feel the clamp that is holding it down, just pop it out as best you can without breaking it. So now that that cable is disconnected, the 10mm bolt is removed, and the wires are disconnected, you can begin to wiggle the damn thing out. take your time and don't get frustrated....and food for thought, its gonna be harder to put back than it is to take out. once you have it out, it should look something like this.
I reccomend taking out the whole assembly, makes it easier to work with. Also, when you purchase a new actuator, its not this whole piece. It is just the part on the right...the part that looks whiter than the rest. so take extra caution because you will be re-using the remaining parts. To take off those two cables, there is one screw and a couple a clips that remove the top cassing.

when you pull this up, you will see something like this...



remove these cables like you would any other cables. first disconnect from the holder, then slide the latch that holds the end in place off, then slide the wires out. Again this is only neccessary if you wish to work off the car. This now gives you access to that one little screw that takes off the actuator.

After removing the screw, the actuator can be pulled upward and off. It sandwitches part of the frame so just pull straight up and it will come off. there is no glue or screws, but if it is giving you trouble, just stick a small screw driver and pry it out. Remove the actuator and install the new one exactly like the old one. Also, please noe that you will need to remove the plastic purple cable holder and install it in the new one. Use needle nose pliers to remove it. Also, its best to do it when the actuator is separate, then just snap it back in the new one. Be sure to put it back on the correct side. Installation is the reverse. Hope this helps out anyone whose door doesn't lock/unlock. If I left anything out, feel free to add insight. total job took about 1 1/2 hours not including trip to dealership and $33. Also I recommend buying part before taking car apart, trust me on this one. Thank you for reading.

 

Thanks for the guide!

I think my front passenger actuator is failing because I hear a "whurrr" everytime I lock my car (doesn't do it when I unlock).

 

it could be the actuator failing. The weird thing with mine is that it worked perfectly the other day, then nothing. Although i have heard that they tend to go out slowly like yours. I asked the guy at the dealer if that was a known problem, he said yeah its a problem with hondas/acuras. But save yourself some money, if you notice it's beginning to fail, and your out of warranty, order the part online and do it yourself. I think i saw it as cheap as $18. The only reason i didn't order it online is cause i'm the kinda person who hates to wait. Plus I'm spoiled when it comes to keyless entry. going a week with this problem and i was bound to leave the car open a few times.

 

what happen to the pics in this thread?? ii think my actuator in the rear door of my car went out, looking to get this fix before it gets too cold outside.