Still not convinced and I’m still digging a bit on the Mopar transmissions. I did find a blurb where Chrysler had admitted to a programming fault with the TCM and this fault involves the converter lockup. Whether it has anything to do with the symptom being discussed I have no idea at this point.
While it’s true the lockup is a mechanical affair, it’s also true that it takes hydraulic pressure to make it work.
The pressure to activate the lockup is applied through the converter solenoid which releases the pressure at the appropriate time to disengage it. (assuming it’s working as it’s supposed to)
It’s also dependent upon temperature and speed. The various Chrysler transmission specs I’ve looked at refer to the lockup being inactive under 43 MPH, 22 MPH, etc. all depending upon the model.
Maybe there’s a hitch with Chrysler transmissions and the lockup solenoid is remaining closed when the key is turned off. I’m still looking at that angle of it.