Will Not Start

I Have 12 Volts To The Positive Side Of The Coil But When I Hook Up The Negative Side It Drops Down Below 5 Volts. Ballast Is Getting Hot. Crank It Over Still Only 5 Volts. This Is Electronic Ignition With ECU Box. I Have A 72 440 Duster. The Engine Wiring Harness Is For Electronic Style With The Plug In For The ECU Box. I Have The Negative Side Hooked Up To The Black With Yellow Strip Like It's Suppose To From The Wiring Diagram For This Unit. Where Am I Going Wrong. I Also Have The Brown Going From The Ballast To The Positive Side Of Coil.