Phantom limbs?

[stimul8]

My 2021 Max XLT does not have power running boards, but after shutting the vehicle off for several minutes I will hear this motoring sound coming from underneath on the side of the vehicle. Sounds like something is going on under there, but there are no visible changes occurring from inside the cabin. Did Ford do something funny like install fixed running boards, but leave running board motors under there?

 

[DWs-TTEB]

These Expys have a 2,000+ PSI fuel pump. When the Expy is off and you open the door in a quiet place you will also hear what I believe your describing (priming). So in this instance, it may be the fuel pump depressurizing