I am attempting to install an oil pressure sensor / sender unit for an automotive application. My concern is with adding a relay to make the internally triggered NO switched contact inside the sensor to be a NC contact.
The issue is that this is not normally a powered contact; it is just switching a ground to tell the internal computer to turn on a light which kills the motor function (reads off of open circuit condition); a fancy oil shut-off more or less.
But that sensor has a dual function; it has a potentiometer side and a switch side, with a common ground tie.
I drew a diagram of my plan but it just leads me to think that when the contact closes in the oil sender, it will create a dead short with the common ground and the other circuit tied to a gauge that reads a pressure which is dependent on that pot's resistance. The two contacts are common when the switch is closed, which is why it cannot be converted to the opposite normal position.
*A fault condition is when contact B is closed, contact B will only close when pressure is below 7 psi. While the cluster fault LED requires an open instance to illuminate, the relay is used to invert the state of contact B.
If there is an easier way aside from building a transistor circuit, I'm all ears.
*Grounds are all common.
*The cluster cannot have any voltage on the relay signal contact.
*The pressure sender/sensor is a coil and wiper with separate contacts for the variable read-out and a contact for an IO connection with common ground to the body of the sensor.
