Why does the system drop out when I attempt to crank the engine?

Check the battery voltage. There may not be enough power to crank the engine and keep the system running at the same time. The system requires a minimum 10V to operate and if the voltage drops below 10V while the starter is engaged it will effectively turn OFF the system. This will cause the Ignition/Start to drop out simultaneously. Be sure 12V+ supply wires are connected directly to the battery or main power supply at a fuse block. Also make sure system is grounded to a battery or a chassis ground terminal,( DO NOT ground with a tap screw).