Defi fuel pressure sensor dead? or defi controller?

Recently my GM air intake sensor died (so it seems) and now all of a sudden it looks like my Defi fuel pressure sensor died as well! Actually, I'm not 100% sure it is the sensor... it could be the defi controller instead, I'm not sure. I checked all the wires and they are continous with virtually no resistance. I have 5 defi gauges all chained together and the fuel pressure gause is the first in the chain; the other 4 gauges work just fine. The fuel pressure gauge is not reading anything and the led is flashing red, which I'm pretty sure means it's not getting a signal. So I figure either the sensor has to be dead, or the defi controller is not inputting the analog signal from the sensor correctly, or it's not outputting the digitial signal to the gauges correctly. I tried switching around gauges in the daisy chain but nothing changed.

I checked the voltages at the sensor... the red and white wires were BOTH 5 volts with 45 psi of fuel pressure, and the black wire was .5 V. I was expecting the black wire to be 0 V (ground) and one of the 2 power wires to be somewhere between 0 and 5 volts, most likely around 2 or so. So I don't know, seems strange to me.

Anyone run into a similar problem by chance? Anyone know how I can test the sensor or controller to figure out what is wrong?

Thanks.