So right after I got my paddle shifters, the manual mode stopped working. Sometimes it will go into a number gear real quick, then back to D, still in manual mode. I bought a transmission shift assembly off a car with 50k miles. (Mine is an 06 g35x with 120k) just installed it and the problem is still there. What should I do? I know this has been discussed before but none of the forums or threads discuss the end solution. I'm thinking a new TCM? Infiniti wants 140 just to diagnose the problem and am hoping I can fix it without taking it to the stealership.
Any help or input would be appreciated, especially from those who have had the problem before. Thanks!

I think this is the right section, if not my apologies

 

There's the problem. Sounds like you created the problem.

 

I haven't installed them yet, this happened right before I did