chrysler/plymouth mechanics

recently purchased a 2002 voyager for my wife ,has power locks, want to
add remote entry ,went to dealer today (saturday) thought maybe
chrysler had aftermarket remote entry equip. was told no by the parts
guy , but he did check his computer and found the plug in module and
remotes available. my question is can i purchase the module and install
in the vehicle? my thoughts are that since the vehicle has electric locks
there should be the harness and plug in the vehicle . thinking maybe
standard in the vehicle wiring harness,that the mfg.maybe uses only one or two harnesses, your input is appreciated.

I have torn through the electrical systems of quite a few cars and it is really hard to say if there will be a harness. If you have power everything there might be a harness but most likely (unless it is an OEM option from the factory) there is no "Plug and Play" harness.
I would recomend going to a local car stereo shop (if you know any teens over 16 they could point you in the right direction :) ). They will be able to help you pick out a system that suits your needs and then they can install it and warranty the installation (harness or not).
If you are like me though and don't want anybody working on your car you can get the wiring diagrams for the car's electrical system from the dealer and use those to decipher the miles of wires layed down in your van.
Happy Hunting