i never hooked up an A/F gauge before because i hate them, but my buddy has one and i need to know how to hook it up. its for a 91 crx si with an ls swap. any help let me know so i can do it and have him quit buggin me.

 

black is ground red is a 12 volt ignition source
and the third wire,what ever color it may be just splices into your o2 sensor.