Complete control harness uses digital circuitry to cover all power supply issues and incorporates a non load carrying oil psi safety switch to ensure that pump does not run when engine is not running. It also includes a "one shot" primer function that energizes the pump for several seconds at key up to prime the fuel system at startup like most modern EFI vehicles do. There is also a manual push button to override the control circuit when bleeding filters!

"Please note that this pump is a centrifugal design. It will not prime itself upon installation and requires a leak free system so as not to lose it's prime. If you do not understand this, your system is not leak free, or you are unwilling to make it leak free please DO NOT purchase this product. The best way to prime/bleed it is by applying light pressure to the tank with the filter bleeder open OR via suction from a hand vacuum pump (Mighty vac) or oil suction gun applied to the filter drain hose. Once this has been done start the engine with the pump off and run or drive for a bit then apply power. The 6.5 should run without an operating lift pump albeit with possibly reduced performance. If not the system has a leak." -JK

This is the switch that controls operation of the lift pump on late model (92up) 6.5's when the engine is running.