Well I have a G37 automatic and when ever I wanted to use the manual shift mode it worked perfectly fine, upshifting and downshifting. Now, all of a sudden when I wanted to downshift for whatever reason it doesn't let me! It will let me upshift perfectly with no hassle but downshifting I have to pull down like 3 or 4 times! I have a big feeling its the ECU but not entirly sure. Any advise will be greatly appreciated!!!

 

try going in forthe tcm TSB . seems like it did more than just the 4-3 downshift for me, also at the same time its reflashing everything it may help.

 

If your RPM's in the current gear are too high,(meaning that when you downshift the gear your selecting will put the rpm's near the rev limiter) It won't let you downshift for safety of the engine. Make sure that when your in a gear, that your RPM's aren't too high and its not the computer stopping you from doing it. Try going in 3rd gear at 3000 rpm's then downshifting. If it still delays and you have to hit the paddle a bunch of times when you try that, there is some other problem than what I just explained, and you should check it out.

 

Whenever I down shift its between 3-4k RPM's. Even when I downshift in high RPM's it'll still lets me! So I don't know what's going on with it.