My relay for my O2 sensor heater is not operating properly. I have no voltage at the sensor. I can hear the appropriate relay clicking under the hood, but it doesn't seem to be switching the current right because if i bridge the circuit with a piece of wire, i get +12 at the O2 sensor, but otherwise i get nothing. I swapped out a couple of different relays (eg horn & defrost) but that didn't do anything. I'm absolutely stumped as to what is happening, why i can get current to the sensor if i bridge the circuit, but i cant get current to the sensor with the relays. Does anyone have any ideas?