Demco Normally Closed Reverse Backup Solenoid Bypass

There are 2 main types of Reverse lockout solenoids: Normally Closed and Normally Open.  Most commonly you will see Normally Open Solenoid Valves, which connect to your Tow Vehicles Reverse Lights, and will then Close the flow of brake pressure when the Tow Vehicle is in Reverse.  A Normally Closed Solenoid, like this one, is also known as a Bypass Solenoid, because it connects to your Trailers Brake Lights, and the main flow of brake pressure is always blocked by the normally closed Valve until it receives power from the Tow Vehicles Brake Light.  This has a few benefits and drawbacks, the main benefit and allure for this type of Solenoid is that it is more accurate (When your Vehicle Brakes, the Valve then Opens and allows the trailer to brake) and it doesn't cause your brakes to lock up when going up or down hills.  A Normally Open Solenoid is easier to install, it's a simpler design with fewer parts, but because the Valve is usually open and only closes when the Vehicle's Reverse Lights are on, the Valve cannot tell if you are trying to brake, or if your trailer is inclined and pushing into your vehicle due to gravity, causing the Trailer Brake Actuator to activate, and activating the trailer brakes.