FPSS problems-
The easiest way to adjust it is simply to disconnect the switch then set your DVM to read Ohms. Read across the switch with the meter, with the car idling, screw out on the adjustment screw until you see a closed condition or around zero Ohms. Then back the screw off slightly more. As received, people have found they could be set anywhere, and its rare that they are actually set corrrectly.
For your info I have set these switches with an ISO certified presure calibration apparatus only to find the switches will turn on and off under vibration. Not to mention the fact this switch has a deadband of like 10-15psi.... Pretty worthless in my opinion.

