Toyota Repair: 03 Avalon Check Engine light, metal particles, transmission failure

Question
My check engine light goes on about once a week and each time it does I get a
P0753 error code which says "Transmission Shift Solenoid A Circuit Electrical".
The car is driving fine. Might this just be indicative of a loose electrical
connection or a faulty sensor? Can I troubleshoot this further myself?

Answer
This indicates a problem with the shift solenoid #1 located inside the transmission on the valve body, this can also be caused by a transmission failure that deposits small metal particles into the oil which can clog up the solenoids so I would suggest removing the transmission oil pan and inspect it for any particles on the bottom, if the transmission fluid is clean and contains no metal particles or clutch material then I'd recommend replacing both the #1+2 solenoids.