Can the BCM be programmed for different responses to switches?
For example, on a 2018 FLHP Road King Police with the ignition on, the PTT (push-to talk) wire from the BCM has voltage on it. Pressing the PTT button turns this voltage off as long as the button is pressed. Release the PTT button, and voltage comes back.
Can the BCM be programmed to normally have NO voltage on this wire, and 12V when the PTT button is pressed and held?

 

I'm sure it is possible but I have not heard of anyone breaking the code to do that type of change. If you have a good relationship with your dealer or service dept ask the about the options on the H-D tech box the mechanics use. There are several cop options that they only turn on for in service LEO bikes and disable when the bikes are traded in.

 

I'm not looking to break the code, just to find out what is available to have the dealer do.

I don't have a good relationship in that respect. They don't work well with these kinds of requests. If I had the information that it can be done, I could go in and ask them to set the PTT button to energize the PTT wire when the button is held and no power when released, and they would oblige...AFTER telling me they'll have to look into it and they'll need my bike for about a week, but they're also pretty limited with the programming capabilities of the equipment.

 

Sounds like you are re-purposing a push button switch.
If so, it may be possible to hard wire it the way you want.
Depending on what you want to do with the button, you may be limited in the current capability of that push button switch.

 

On a CAN bus system the switch sends a signal to the BCM. I don't think it is possible to use the switch as a switch if that makes sense.

If it can't be done you could perform the task electronically to create an inverter.