here's the DTC below from a search, if you have a spare TPS it may be worth a try, otherwise id check the harness connector on the gearbox, pull it off and back on, also do the same on the ECU. Also looking at the wiring diagram pins E14 & E15 are solenoid wires, id unplug the ECU and use a multimeter to check the resistance on that end, will help you ID if wiring is the issue, if wiring is ok it should read 3.5-4.8 ohms at 20 degrees C.
http://pcmhacking.net/forums/viewtopic.php?f=32&t=12
DTC 73:
PRESSURE CONTROL SOLENOID (CURRENT ERROR)
The pressure control solenoid is a PCM controlled device used to regulate transmission fluid line pressure. The PCM looks at TP sensor voltage, engine RPM and other inputs to determine the line pressure appropriate for a given load, then regulates the pressure by applying a varying amperage to the pressure control solenoid. The applied amperage can vary from 0.1 to 1.1 amp. The PCM then monitors the amperage at the pressure control solenoid low line and if the low line amperage varies more than 0.16 amp from the commanded amperage for a duration of about 1 second, Diagnostic Trouble Code (DTC) 73 is set. Once DTC 73 is set, the pressure control solenoid is disabled and full line pressure will be applied until the next time the ignition key is cycled. If upon restart, the current error does not exist, DTC 73 will remain stored but the pressure control solenoid will resume normal function.
Test Description: Number(s) below refer to step number(s) on the diagnostic chart.
2. This procedure verifies an amperage difference of more than 0.16 amp between the actual pressure control solenoid current and the desired pressure control solenoid current, the PCM's ability to control amperage to the pressure control solenoid.
3. This part of the test checks the pressure control solenoid for internal shorts and integrity.
Diagnostic Aids:
Check for poor connections at PCM and especially at the transmission pass-thru connector.
Pressure control solenoid resistance should be between 3.5-4.8 ohms at 20 degrees C.
When Diagnostic Trouble Code 73 is set, the transmission will have harsh shifts and maximum line pressure.
The PCM controls the pressure control solenoid by commanding current between 0 and 1.1 amps. 1.1 amps corresponds to minimum line pressure, and 0 amps is maximum line pressure (if solenoid loses power, transmission will still have maximum line pressure).
