Had a dig around Alan and unfortunately I don't have a wiring diagram but......From memeory, I think there's 4 pins in the connector? only 3 of them are electrical connections, V ref. GND & signal, the other cavity is a tiny breather tube.

If your'e using clip you should be able to compare desired vs actual pressure? If so, you need to see a discrepancy less than about 0.2 bar at idle. HTH.