Most common cause for loss of reverse?

[Jerrypc]

Hi All, I was looking for input on some of the common causes for random loss of reverse. In my situation, reverse didn't "wear down over time." Just one day shifting the gear in reverse simply did nothing. Reverse now operates the same as neutral, revving the engine does not move the vehicle backwards. I also lost overdrive on the same day, but can drive forward still. The car only has 150,000 miles and it's a 2003, so that sounds to me like that is a little early for a full transmission blow up.

Anyone experience anything similar? Is it worth it to drop the transmission pan and look around to get more information on the problem or would that be a waste of time?

Thanks!

[smj999smj]

There are line pressure tests that can be performed. The most common cause of this, however, and not just specific to Nissans, is when the reverse clutch snap ring pops out of its groove in the reverse drum. Without the snap ring in place, the reverse drum piston can't compress the steel and friction plates in order to get reverse to operate. The fix for this would be to replace the reverse clutch drum and snap ring, but some might replace the whole reverse clutch drum assembly. This requires removal and teardown of the transmission, which, depending on age and mileage, may make more sense to overhaul or replace the transmission.
Of course, it makes sense to check the basics like fluid level and condition, the shift cable and cable bushings, etc., before condemning the transmission. A valve body issue could also cause this problem.

[MadDogJacoby]

I got my 1998 Pathfinder from an auto wrecker. They said the reverse went out, only codes were for the 02 sensors. It would start, run, shift normally into the gears except for reverse. It would stall almost immediately. Looked up just about every possible cause.

Turns out, it was the upstream 02 sensor on the driver side. (Can't recall which bank that is), and now it shifts perfectly fine. Saved a perfectly good car from the crusher. Now, it owes me the rest of its years