I'm trying to install an aftermarket tach in my 84, but can't get anything out of it. I have it grounded to the dash, the red wire is hooked to the only terminal marked "IGN", and the green wire is plugged into the terminal on the cap marked "TACH", but no luck. I was told on another site to tap into the white wire coming out of the tach port on the cap, but that only goes to the plug for my ac compressor. There are 3 other wires coming out behind the white wire: Brown, Black, and Pink/Red. Do I need to tap into one of those to make the tach work? (I can't post a photo of the wires as the photos are to large.)