The McCain LED EMS sign is offered as a complete new sign or as a retrofit kit to convert older fluorescent signs over to LED signs. The conversion process uses existing mounting points within the sign housing and uses no pre existing components other than the main terminal block. A solid state power supply, dimming system and harness mount on a bracket that will replace the fluorescent ballast bracket. A new panel mounting bracket replaces the reflector bracket with the new message panel and honeycomb attach to this bracket. A photo cell ambient light sensor provides auto ranging dimming in a range of 0% dark to 100% full bright. The photo cell can be mounted either on the top of the sign or on the side of the sign for double high sign installations.