02 sonata v6 P1600 P0740
 

Can't figure this out. Sounds like possibly a short in the wiring between the tcm and ECM or tcm and battery? Started when the car went through a very deep puddle

And now P0335 also. I recall having this issue when I changed the output speed sensor a few years back. Can't recall how I resolved it.

P1600 is a communication cable problem between the trans and computer.

P0740 is a problem with the lock-up clutch in the torque converter:
OBD2-OBDII Code P0740 HYUNDAI - Torque Converter Clutch Solenoid Valve | Engine-Codes.com

P0335 is a problem witht he crankshaft position sensor:
P0335 Crankshaft Position Sensor A Circuit Malfunction Engine Light Code

I think the last time this happened it was the wiring harness to the output speed sensor causing the problem.