When I set my alarm my doors used to lock, this has stopped happening, but when I manually operate the drivers door lock from inside the car the passenger one operates as well. So I am thinking that it is the drivers door lock actuator. In an older post this picture has posted saying the metal gear was slipping on the motor. (We used to routinely solder gears like this to motors on slotcars so an easy repair.) There were a couple of reply's saying you could buy them at Jaycar. (link broken) I assume it was this: http://www.jaycar.com.au/productView.asp?ID=LR8813 Is the one from Jaycar a direct replacement other then wire connectors ? Is the one pictured the OEM lock actuator ? Am I on the right track ? Excuse the picture quality its a cached copy.
I'd be more inclined to believe that the aftermarket actuator rod is at fault. Most keyless entry installs I've seen on 300zx's involve using aftermarket solenoids, in conjunction with the factory operating central locking system. Putting it simply, its most likely that the rod from the aftermarket master solenoid (4-wire) has come loose from the factory setup. This can be proven by trying to operate your remote while inside the car. Should you see a slight movement in the interior handle door lock, usually about 5-10mm, then its a matter of locating where the aftermarket solenoid rod has been attached to the factory setup and re-tension the clamp (normally 2 small grub screws) Cheers Michael
The most common reason for the door lock actuators not working is the wires that go to it break / crack where the door opens ( like bending your elbow ) constantly over the years. If you check in the front opening where they bend you will more than likely find a crack / break in the wiring. The Jcar ones fit just check how many wires go to your actuator and buy one the same , but I would bet it will be broken wires. Cheers Dave