A friend of mine ha a Dakota with the 545RFE.
After having parked for 6 weeks he gets an P0944 (Transmission pump lost prime).
The vehicle does not move in gear or reverse, the fluid level on the dipstick is slightly over max hot with the engine stopped, and does not change with the engine running.
I removed the line pressure sensor and started the truck, there is no oil on the line pressure sensor port.

My theory is that the pump is shot, but I would like to avoid pulling and tearing apart the tranny if it is not necessary.
The truck has approx. 30 k miles and did not act up until he parked it.

TIA

AlpineRAM

 

The problem is solved.
The o-ring between pump suction filter and pump case had worked itself down the filter tube. The good thing is that it failed finally with the truck parked, no other damage to the trans.

AlpineRAM