I have to go look to be sure, but I think S5 is the relay board output wire to the MSD box or negative side of the coil if you connect it directly. Look up where Pin#36 comes out on the relay board to confirm.
I tried this (from the megamanual...) and never got it to work that way, so I just plugged it directly into the pickup coil like in the picture I posted above. Now my VR circuit reads the square wave of the Hall sensor on the crankshaft.
To further confuse things, you could be like Randal and use the VR input to read the square wave of the HEI module, it also requires a couple special turns of the potentiometers but isn't difficult.
Comment