The Nissan Path

I have a 2008 Pathfinder LE I bought a month ago with 67k miles. Everything has been great. The dealership claimed to have done a thorough check of the radiator and trans for any signs of damage due to the mixing issue. I bought a CSF radiator with plans to swap within the month.

Just today I was unable to back the truck up a driveway. It seems like the trans is slipping in reverse. At first I thought maybe it was ice, but it seems to be happening on dry pavement and even a flat parking lot now. I tried 2wd, auto, and 4hi with the same results. Forward drive seems to be unaffected.

Anyone know what's happening? Is the trans blowing up?

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.

Thanks.

I just brought it in. I sure hope whatever it is will be covered under warranty. I bought one for a year and the dealer supposed included one for 30 days.