Cruise Control Headache ('16 RTS) - Goes ON, but will not engage! Any ideas?

[Old Prof]

Based on your symptoms so far (was working, no change when flasher disconnected) the most likely cause is a sticking brake switch as noted above. The switch is an SPST N-O microswitch which provides +12V to both the ECM and the brake lights. The brake lights (and taillights) are LEDs so respond instantly to the +12V. Any flicker in the brake lights is also observed by the ECM. If the ECM has debounce logic I doubt it's longer than 50ms.

Best wishes.

I appreciate your advice. "If the ECM has debounce logic I doubt it's longer than 50ms." Translation please.