Just to clarify, when you turn the cruise on, does the dash light come on to show the system is on and it just doesn't set? Or when you press the on button does the dash light not even come on?
I attached the description of the system and the wiring diagram. As you can see from the diagram, the switch inputs are all a direct feed to the PCM. I assume you are saying the horn still works to rule out the clock-spring?
If the light doesn't come on at all, I suspect the PCM is not getting the input from pressing the button. Is there a chance that this has not been working for a while and not related to what you installed? How often do you use the cruise or do you remember the last time you used it?
If the light on the dash does come on, I suspect your brake switch may have failed and the PCM thinks the brakes are so it doesn't activate the system, however the light on the dash should still come on.
Last thing, is we need to see if there are any codes. If you have a circuit issue, I suspect you have some codes. Let me know if you have a scan tool that you can see live data as well as codes.
Images (Click to enlarge)
Sunday, June 9th, 2019 AT 4:58 PM