I have a 2007 G35 coupe with 150,000 miles and i bought it about a month ago it runs great in every aspect as it was a one owner car, but the the tiptronic manuel mode does not work. I have tried resseting it and i removed the shifter and cleaned everything good. The metal switches where you shift up and down both click and work fine i just cant get it to activate into manuel mode. any suggestions would help, thanks.

 

 

I've struggled with this issue for a while. Double and triple check all of your grounds; there should be two on the passenger side of the timing chain cover, a large brassy-looking one under the coolant reservoir, and one somewhere on the passenger side of the battery compartment/right in front of it. Scrub those down with a steel brush and use some sort of protectant to avoid more corrosive.

Make sure your fluid is at the correct levels, IIRC boiling/low fluid will cause the transmission to not let you enter manual mode. Aside from that, check all plugs going into the shifter and the switches themselves.

It's an annoying problem that could be bad grounds, a dying microprocessor, a dying transmission (learned that one the hard way), or just a switch going bad. The shifter assembly is near $500 new, so hopefully it's just the grounds.

After getting my new 5AT installed with a new shifter assembly I was still having issues (no MM, rejected downshifts (still happens sometimes), but after a month or so of driving and a road trip across the U.S., it has refused MM once (totally randomly, was driving freeway in WA in 25 degree weather, no hot fluid there) and had a couple glitches with trying to continually downshift, but otherwise works great. Nissan really isn't that great with automatic transmission software.