The phrase refers to the correct operation of an electronic device integral to safely towing a trailer equipped with electric brakes. The device, mounted within the tow vehicle’s cabin, allows the driver to manually or automatically engage the trailer’s brakes, proportionally mirroring or adjusting braking force relative to the tow vehicle. For instance, increasing the controller’s gain setting will cause the trailer brakes to apply more aggressively when the tow vehicle slows down.
Correct operation is paramount for maintaining control and stability, preventing jackknifing or trailer sway, and reducing wear and tear on the tow vehicle’s braking system. Historically, inadequate trailer braking systems were a significant contributor to towing accidents. Modern electronic controllers offer substantial improvements in safety and control compared to older surge brake systems, particularly in emergency braking situations.