aFe POWER BRAKELOGIC exhaust brake controller is a simple plug and play module that electronically closes off turbocharger vanes to provide engine braking. It also controls the transmission to downshift to enhance braking. The factory tow haul switch will allow you to turn on the unit and simply tapping on the brake will engage it. The aFe POWER BRAKELOGIC module will help maintain and control your speed during steep descent. It is perfect to use while a trailer is connected or heavy load is carried. The engine braking created will eliminate overuse of the brakes and prevent them from overheating. Recommended for vehicle with automatic transmission.