Electronic Control Module
The module uses 6 wires (7 wires on 1975 models). The Red and White wires are ignition feed. The White wire is ignition primary circuit with engine cranking and Red is ignition primary (1.3 ohm resistance) with engine running. The primary current is turned on and off by the control unit through the Green wire between module and coil.
The Orange and Purple wires transmit signal to the module from the distributor stator/magnetic pick-up coil. The Black/Green wire is the distributor ground circuit. The 1975 ECM has one additional power feed wire. A Blue fusible link wire protects ECM from voltage spikes. All other wires are identical.