O2 P0141 & P0161 faults

I have a 2001 4.7L Quad Dakota. My error codes are P0141 & P0161, O2 heater sensor circuit malfunction. The sensors have 4 wires:Blue-O2 signal, White-ground, Black1-12VDC, and Black2-heater. I pulled the sensor plug and found ground and 12VDC, but the heater line is shorted to ground (without the sensor plugged in). I read an explanation that the 141 & 161 codes mean that the heater circuit is drawing more then 2.25A, which I could believe if the heater line is shorted upstream of the sensor. When I attempt to read the resistance of the sensor heater (black to black) it appears open. Does this make sense? If the harness is shorted, I'd hate to blow $250 on two new sensors and burn them out. Does anyone have any ideas????? The truck won't pass inspection with the faults.

you must be very carefull with these sensor circuits as the heater element is pulsewidth modulated through the engine controler and this circuit is very sensitive to damage if not testing correctly could take pcm out

So do you tink that you can measure the resistance of the sensor heater, or would it be better to read the heater current? I had read that the heater draws 1.5A when its cold, then heats to ~100mA when at operating temps. I'm also wondering of my PCM is bad. Right before the MIL light came on, the fuel gauge was going crazy for about a week-then the light came on. Now the fuel gauge reads good.