Abstract: An electrical relay testing device that provides color-coded indicator lights to test vehicle circuit boards for any 12 volt or 24 volt systems, drawing 15 to 150 amps. The device contains an internal relay, standard relay terminal connections, and at least two external indicator lights. Once the device is plugged into a vehicle circuit board, if the relay terminals are properly working on the board, both lights will illuminate. This device greatly simplifies the process of troubleshooting electrical and electronic systems of vehicles.