P1780 replaced switch ecm and harness

Question

My car originally had p705 and was driving like shit. Low constantly lit up and Drive or park or whichever gear shifter was is was illuminated on dash, car has no clue what gear it's in and the rpms Rev continually almost while driving and car will only accelerate from stop in low gear and I manually shift thru gears. I've changed the transmission sensor itself, the ECM and the wiring harness in the dash however I've not replaced the harness that goes from ECM thru firewall...car still driving EXACTLY the same as before I replaced anything..I have the complete wiring harness for the car should I replace all the engine wiring as well to fix problem?..now the p0705 code is gone but p1780 is coming up and my check engine light is NOT on any longer