You can install both the Curt 4-pole wiring harness # C56389 and the Autowbrake Trailer Mount Electric Brake Controller # 3430001 (and the required 7-way kit # ETBC7L) in your 2019 Buick Regal TourX but each one of these items must have its own dedicated power connection to the vehicle battery.
I realize its no fun crawling under the car to route those power wires but this is critical for safety and for proper operation of these devices. For a worst-case example, if there were a fault... view full answer...