96 with O/D light flashing, EPC solenoid?

Van seems to run fine, overdrive goes on and off, the reverse to forward shift seemd hard. I have factory shop manual and a shorted EPC, electronic pressure control solenoid is one possible cause. After looking thru book several times, I think tranny has to be pulled to replace this part. Does anyone know for sure? IT is in same spot as othe solenoids that control shifting.
I replaced the range selector switch several months ago just for preventative maintance.
Other possible causes?
If will have to try and see if I can measure line pressure per the table this weekend.

I would take it to a dealer and have read the transmission codes.
Well worth paying them to know what the code(s) is(are) before opening the transmission.

I verified that line pressures were going out of wack, it shifts hard from neutral to drive.

I was able to find the solenoid resistance values in manual and it was okay, I hooked up a battery and heard it click, key on I saw 12v at connector, added a can of sea foam trans medicine, still not working.

Then I disconnected battery for a while and that seems to have fixed it