Instead, I used this piggyback spade connector, which connects the instruments to the lighter ground and provides a second tab for the lighter's original ground to connect. With this, the gauges had power. Instructions also suggested drawing power for the instrument lights from a circuit that's already dimmed with the factory instruments, such as the lighter's bezel light. I'm not sure whether that's a bad idea or Project 325 has a problem with that circuit, but after some time spent characterizing the available power with a voltmeter, I established that was not going to work. With more time I'd have gone to the dimmer switch, but to get the job done I simply hooked the gauge lights to the gauge power. They are lit any time the car is on, but it's not bothering me too much yet.