I mentioned this before in a thread but I don't think it got answer. Since the tach wire is the only wire is see on the relay board that goes a gauge, is this also responsible for powering the other gauges as well? My gas, speedo, tach, do not work when the car is running.
Right now, if I hook up the purple/black wire coming from my relay plate to the - side of the coil, it causes the car to die. I evidently have a short somewhere in that wire some sort of theft thing installed maybe that is causing this.
I am in the process of ripping it out and seeing what I got going on.