On the GlowShift boost gauge there are four wires. The orange and purple control the lights on the needle and dial. The yellow is the memory wire for the colors and the black is ground. You must connect both the orange and the purple to a 12-volt ignition switched voltage. For example, a good source that turns on and off with the key is the radio. The yellow wire needs to be connected to a 12-volt constant voltage, and the black wire needs to be connected to a good ground. This gauge does not have connectors, so we recommend that you use a male and female style connector to install this gauge.