This is a cut & paste so the all caps isn't me...

P0748-PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS
When Monitored: Continuously with the key on.
Set Condition: This code will set if the voltage detected on the Governor Pressure
Solenoid Control circuit at the PCM is different than the expected voltage.
POSSIBLE CAUSES
P1765 DTC PRESENT
INTERMITTENT GOVERNOR PRESSURE SOLENOID
TRANSMISSION RELAY OUTPUT
FUSED B+ CIRCUIT OPEN
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT OPEN
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT OPEN INTERNAL
TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO GROUND
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO GROUND INTERNAL
TRANSMISSION RELAY OUTPUT CIRCUIT SHORT TO GROUND
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO SOLENOID CIRCUITS INTERNAL
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS
GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS INTERNAL
TRANSMISSION CONTROL RELAY - POOR CONTACTS
PCM - GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT

One way or another there is a hard fault in the Electronic Pressure Regulator circuit... Could be a shorted solenoid, an open solenoid, a wiring issue or a PCM problem.. Disconnect the battery & the PCM.. Find out which pin from the PCM is the EPC signal, ohm it to ground, (should be open) If not something is shorted to ground... Also ohm it to power (should be a reading that represents the resistance of the solenoid) if it's open the solenoid may be open but I'd be checking if the solenoid is plugged in... Wouldn't be the first time someone unplugged a solenoid to move a wire out of the way & didn't plug it back in before bolting the pan on...