Help, please... 92 HB Auto trans: Always in NEUTRAL.

[Mark53]

Hi, people.

Another newbie here...
NICE forum... quite active, and Lots of cool info, helpful people.
I've searched a bit, but this problem just seems too weird.

1992 Nissan HardBody Pickup, 2.4L engine, 2WD, Auto trans.

Just cruising along the road at about 35 MPH,
it just sorta' went into Neutral, all by itself.
No bad noise, it just started rolling (like... in Neutral).
Now, Park is the only thing that works.
If moved to any other gear, there's no bad noise at all,
and it does not Get into any gear (Low, Drive, Reverse, etc...),
AND there's No reduction in RPMs at all.

Put a new (allegedly rebuilt) transmission in, 4 years ago, for $600.
Since then, it's driven only about 8000 miles.

Pulled the pan from the bottom of the transmission...
found just a bit of sludge, but no metal parts or even shavings.

Any clues? What could cause this?

I found the FSM on this site, and it says maybe the problem is in the "Control Valve Assembly".
But, it tells me only how to Remove that thing.
How do I know if something in there is defective? How to test the parts in that Assembly?

Thanks very much, in advance.

Mark53

[PapaSmurf2k3]

Unfortunately its difficult to test anything in that assembly.

I haven't torn one down, but you should be able to replace it without dropping the trans, right? It should just be behind the pan and filter. I would say your best bet is to try to get another valve body assembly and swap it in (and hope that fixes it), assuming you've already done the obvious fluid level and shift control mechanism inspections.

If you put the new valve body in and it DOESN'T fix it, then you're probably looking at another rebuild. Some seal either in the pump, or the gear clutches could be blown.