When you by-pass the switch and it cranks then there has to be voltage going to the coil...right? You should voltage at the coil when you turn the switch on. Where do you have the hot wire going from the MSD box connected to? On my 67 Barracuda there is a blue wire and a brown wire that I had to connect together (after removeing the ballast resistor) from the switch to the ACCEL 300+ ignition system's hot wire or it would not crank. At first I hooked to the blue wire and it wouldn't crank but when I hooked the brown and the blue together then hooked those to the box it fired right up. I know that you should have voltage at the amp guage on the red and also on the black. The black is going to go to the fuse box and makes everything hot.