Postby smj999smj » Mon Dec 26, 2016 7:01 pm
It's impossible to say what the problem is without doing the diagnostics. It "could" be a bad reverse solenoid on the valve body; Nissan doesn't sell these separate from the TCM/valve body assembly, but, they can sometimes be located on the aftermarket with some online searching. It could be an issue with the valve body, itself, and while it is a costly repair, it is much less expensive than replacing the transmission. It could be the reverse clutch drum, itself, which would basically require an overhaul...or, at least, R&R and teardown of the transmission.
The factory service manual provides a symptom chart in the automatic transmission section which will gives the possible causes for a no reverse condition and rank them in order of likelihood. It will also provide a link to where the diagnostic steps are in the manual to follow to confirm exactly what the problem is. This may require doing a stall test and line pressure tests along with circuit tests and will require transmission oil pressure gauges, a capable scan tool and a multimeter. Some of the tests you may be able to do yourself, but some may require taking the vehicle to a reputable transmission shop, dealer or an independent shop that has a technician competent in transmission diagnosis.