hey wire issue

ok i got a digital air gauge and how do i wire that its only a two prong i got the wiring down for the guage but dont kno it the sec. prong is a power hookup or a ground hookup

What brand is it? What are you trying to wire, the sending units or the gauge or the brain or????

i got a digital guage but its from horn blasters i kno theres a signal prong but i dunno if i hook up the other one as a ground or hook it up to a power

its the sending unit im tryin to wire

one is a ground the other goes to the gauge