What is a Transponder Bypass?

[Veinot]

I have been google searching for an answer and I have gotten alot of people looking for one but nothing on what it is and what it does.
Its called a Transponder Bypass Module, and it bypasses something in a vehicle but I don't know what and for what purpose...
Does any one know exactly what it does?
What it is used for?
How it works?
What is programed into it?
I came accross it doing searches related to engine swapping and ECM/ECU reprogramming and integration.
Anyway, thank you for any help with this

[Towncar]

Assuming your referring to PATS vehicle security....

The transponder & reciever are built into the ignition keys and steering column. The vehicle wont start without those two components pairing first.

For remote start systems, you will need a transponder (PATS) bypass module connected to the remote start system for the remote to be able to start the vehicle without the transponder key.

Those bypass modules sell for about $40 to $50 USD. >> here's << a sample.

[Veinot]

OK, makes sense. It came up in a search I was doing in regards to engine swapping, ECU reprograming, piggybacking ect... I was hoping it was something you could use to interface an aftermarket or a different ECU,ECM,PCM to another vehicle so that it will understand and control the new engine that may or may not have been an option for that model.
Is there anything that would allow this? Or is there away to just reprogram a V8 PCM,ECU,ECM to run a different V8?
I know they reprogram them for SuperChargers and and other mods, I was just wondering if they can be setup to run different engines... as long as the engine has the right amount of cyl

Anyway Thank you for your response I know I cannot use that for what I want to do lol