The Oil Pressure Switch is in series with the 12v positive supply to the fuel pump relay and the factory ECM is still in place in that circuit for the time being, which bypasses the OPS during key on, supplying 12v to the fuel pump relay. The firmware/Jaguar board supplies the connection to ground through the Fuel Pump FET (Low Side Driver) completing the electrical path to allow the fuel pump relay to be energized.
I need to finish the wiring harness modification to get rid of the factory ECM/Oil Pressure Switch as I don't see the truck leaving my possession any time soon. It is too much fun!
