need help, no turn signals.

Turn signals not on, front or back. I took the old bulb out of the driver rear side and turned the left blinker on, took a test light and tested the two wires. One has power, the other does not, I'm guessing this is a ground? Or is the bulb grounded by the body, and both wires are power? This is what I initially thought, as this is a two stage bulb... The signal flashed looks pretty new, I know nothing about them, but when clamped my test light on it, touched the light to power and grounded the flasher, the test light Came on steady....