Thank you. Actually I/O board putting out pulse that turned on and off green light. No schematic on board. When tower light added, a relay was put in place of light, using no and nc contacts to change from green to yellow. When in cycle, pulse is solid 5 volts turning on relay, turning on green light. Cycle done, pulse on and off, turning on and turning off relay, cycles green and yellow lights. Would like to have either solid off or on.