Working on a ups truck with a 2014 gm 6.0 with a E78 PCM ,no power ,backfiring into intake on acceleration,codes p0174 and p0171,while testing found that the PCM is not sending 12v to the crank sensor.replaced PCM and same problem,I'm testing at the PCM so I'm assuming the wiring to the sensor is good,I can jump 12v to the sensor and the fuel trims zero out .the funny thing is that the PCM puts out a steady 5v to the sensor not 9 not 4 but 5v?any ideas