OK. In Start power connection is made to the brown wire and yellow wire coming off the ignition switch in the diagram above.
Yellow represents the power to the trip the starter relay.
Brown represents Ignition 2, only used for starting. It connects to the coil side of the ballast resistor.
Above is a diagram to make it simpler to see how power flows.
Best to check the wiring diagram in a '70 Dodge or Plymouth Service Manual for the actual colors and connections.