I have a digital boost gauge ..think it's a dragon guage !! Anyway I have 3 wires which are connected to a black plastic piece nr the bov pipe ..that's not my problem , whenever I put power to the guage it comes up -12 and doesn't go up or down under drive . There is a green lead black and red and I have now disconnected all of them as I don't wanna mess around with wires . Is there anyone that can help me out ? Might be simple fix but I thought boost guage should to have a pipe connected ? Many thanks in advance , bridgend area if anyone close

 

With my defi gauges it has a boost sensor and that Tees into near the bov

The sensor then connects to the control box and then to the gauge

Has yours got a control box or sensor

Steve

 

I will have to take a pic as I'm not to sure I know it connects to a plastic circular piece just next to the bov

 

It depends on the wiring. My Prosport gauges had a permament live to the cigar lighter amd earthed to the chassis on the transmission tunnel. The vac hose was t-ed in between the inlet manifold and boost solonoid if I remember. There are guides in the general technical section.

 

Yeh I have no vac hose this is why I find it weird just 3 wires ..hate electrics hahaha

 

if it doesn't have a vac line then it will just be a digital gauge. The sensor checks pressure and sends the info to the gauge via the wires. Should be 3 wires - one for ground/earth, one for 12v switched live (comes on with ignition) and one for the sensor reading.

you say you have green, red and black so most likely black is ground, red is switched ignition and green is signal. If you still get the -12 with that then try switching the green and red over.