What Is An Automotive Relay, and What Does It Do? In the simplest terms, a relay permits a small, independent, low-current circuit to control an independent, high-current circuit.

The 15A Relay switch is compatible with HAI's Auxiliary Switch (Part number 37A00-1) for 3 - or 4 - way applications. HAI's HLC line is a fully two-way communicating lighting control system.