On my 2005 Infiniti FX35 the Passinger Door and Rear Hatch Locks will not open. Intermittently they will work, but it seems to be getting worst each day. Is there a way to diagnose which actuator is going bad? thanks

35 or 45 , which is it.? typo?
well if it has strut cartridge they are bad
these

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=INFINITI+fx35+rear+hatch+strut+cartriges&_sacat=0

If it opens from the outside, check on the door itself near the latch assembly for a little black lever that moves back and forth...that is the child safety rear door lock and when engaged, wont allow the door to open from the inside...setting the lever to free position should allow door to open (pg 3-5 of owners manual)
https://owners.infinitiusa.com/content/manualsandguides/FX/2008/2008-Infiniti-FX4535.pdf

Hi
unfortunately no the struts are not repairable, you need new pair.

The problem is the Door lock actuators and when I went to the dealer they want $467.90 to fix just my driver's side door, but after almost having a heart-attack from the dealer's estimate, I checked on ebay and found a Kit to fix the door lock for only $59 so i ordered one kit (shipping was super fast) it came with very easy instructions on how to install the kit, so I installed about 4-months ago in under 1HR and now everything is Back to normal, I can unlock/Lock using my original OEM key fob and also using the power switch on the door, so everything work as from factory ( no need for aftermarket alarm or remote) ... !!!! here is a link of the kit that I purchased. The seller is green-seller1975 and item #111291472359

try holding button longer

Ok we have had this problem on the hatch of our 2003 FX35 and are about to return to the dealer for the 3rd time in just a matter of months! They have ordered and replaced the part both times. So is there any suggestions on how to get this resolved? We live about 60 miles from the closest dealer and it's getting beyond frustrating!

remove rear brake rotors on 2005 infiniti fx35

need to pull door panel off there is a cable that op. the window they get twisted in motor poss. need window motor..

First, on the rear hatch, there is an actuator. On FX, when you close the trunk, it kind of **** the hatch closed all the way. When you press lock on the remote, this same actuator locks it as well.
Now,
1) when you unlock the car from the inside, go back there and press the button to open the hatch door manually, do you here any noises?
2) Close all doors, go back close to the hatch button and using the remote , lock the car and then unlock the car. you should hear a sound from the actuator locking and unlocking the lock on the rear hatch!

If you don't hear this, your actuator is inop.
Next step would be to check the fuses inside the car, on the left bottom driver side, and outside on the battery compartment.
It might be just a fuse.
If all fuses check ok, your actuator is most likely gone! Not ea expensive fix, just time consuming!

NOW, if you can hear the noises, then something is either broken inside the actuator or one of the cables is loose!
Hope that helps.
Also, what year and miles on your fx?

lubricate door hardware, locks, etc.