Constant Downstream Occlusion

What line set are you using.  Check occlusion sensor calibration low high and mechanical. Sounds simple.

Dumb question however have you replaced the battery to see if that is causing your problem. 

ChemoMan, I literally covered all aspects of the occlusion detection system and I'm throwing you a dumb question? GTFOH, ChemoBoy

The pump doesn't even attempt any infusion at all. It simply detects downstream occlusion. Yet, it will prime just fine...After replacing the sensor and completed calibrations, I'm here seeing if anyone has been through this before. Thanks.

There are certain things the processor looks at during a reguar run and things it doesn't look at prime. The motor drive signal is different during prime. I think you have a processor problem or a motor problem. You might want to send it in to B-Braun. If you have been trained by B-Braun there techsupport is pretty good, otherwise no way are you getting help from them other than a RMA. 

If your battery doesn't hold correct voltage you can get all sort of problems also the door has a magnet in there make sure it's in tact 

If your battery doesn't hold correct voltage you can get all sort of problems also the door has a magnet in there make sure it's in tact 

How do you calibrate the occlusion sensor?

Check out section 4.11 of the Service Manual.