I've just fitted a new boost gauge - Prosport stepper type.

It has 3 wires (red, black, white) that go to a MAP sensor.

However, the gauge reads against the bottom stop all the time (i.e. not '0' bar, but -ve manifold). When the gauge is turned on, it spins the needle up, as per the 'opening ceremony', so I know that the gauge has power and the stepper is working.

Also, If I disconnect either the black or white wire from the MAP sensor, the gauge reads maximum and flashes - but the red wire has no effect.

My 'basic' understanding of this type of system is that the 3 wires are 5v, 0v and signal. I'd guess at red for 5v, black for 0v and white for the signal.

If this is correct, should I see 5v on my voltmeter between the red and black wires ?

Does anyone have any ideas ? - Or does anyone live near Stafford, who I can borrow a sensor or gauge from to connect in ?

Ta,

Mark