Thank you folks, in advance for any insight into my problem:
I am driving 35-40 mph and it feels like the automatic tranny slipped into neutral. No big bang... no fluid anywhere... engine still running fine... and never any prior slow shifts, slippage, weird shifting, etc. to tell me "hmm, I think my tranny's going to go next month".

ALL gears are dead and no weird sounds, shifter shifts into all gears good and tight. I added 1/2 qt of fluid, as it was down below the cold mark, once I got troubleshooting. But never any leaking fluid in the driveway. Car has right over 200K and new CV shafts Jan 07 (fwiw).
What's been done:
Ran transmission codes and the long blink is #7 ("Torque Converter/Clutch solenoid valve [=lockup] circuit")
Q:Can anyone tell me what to check on this circuit? Could I get lucky with an electrical malfunction, since there was no 'bang' and no grinding noises (even now when I crank eng.)? Oh please let this be true. OR... is it a dead Torque Conv.?
What's not been done:
No cleaning of connectors at TCU, or elsewhere. No checking of other things, as I don't know what to check. I hear certain things should be checked for functionality BEFORE you run tranny codes, but with all gears gone, can't I cut to the chase?
Thank you SO much for any guidance. I'm getting scared. and all this when I'm moving by the end of the month!!

 

Does it move in any of the gears?
I have heard of cases where the torque converter stripped. To find that out, the trans will have to be pulled.
I would check all the electrical connections for cleanliness, and clean any that are corroded. Also check that there is a good trans to body ground.
What color is your transmission fluid?

 

when mine died it did the same thing. i never performed a proper autopsy but my money is on a dead oil pump, or a stripped t/c. it made a sound like sticking something in a running fan when i revved it, and it made no attempt to go into any gear.

 

if it is an electrical issue, it should lock in 2nd gear when D is selected, even if you completely unplug your TCU, you can still drive it like this.
Like others have said, sounds like a stripped converter (centre spline can strip), or a dead fluid pump. Either way, the transmission will have to come out.

 

Yep, I was afraid of that (tranny out). The fluid is nice and red. I'm 2nd owner and keep up with the maint. (somebody asked). But as someone mentioned, theirs was making a sound when revved, like sticking something in a fan. Mine does NOT do this when revved. I was so hoping for an electrical, not mechanical.

If you guys think it's worth cleaning all connectors back to TCU, that's what I'll try and I'll be sure to post results. I found something on an older thread referencing a connector around the master cylinder area that has direct results/ref. to the tranny and shifting. Anyone familliar with this thingie?

About disconnecting TCU and seeing if it runs in 2nd gear... Is this called 'safe mode' and if so, is this not 3rd gear, not 2nd?

THE BIG Question: Anybody have a good VG trans OR... Want to buy a great Maxima with no trans? I have video of the engine running... smooooothhhh...

 

Oh, about the fluid pump... would this not show up as a code? I've had a trans. shop tell me to see if the fluid level rises once the tranny gets warm. If it doesn't, the the pump is gone.

THEN I've had another mech. say that's totally temp related, not pressure related and will tell me nothing about the pump. Just break into the line from tranny to radiator and take a press. reading. I can do that. Anybody know what press. I should be pulling?

 

14 PSi according to the 94 FSM AT-331

 

Got a link for that?

 

You could be right, it might be 3rd, but there is a safe mode where the TCU bascially disables itself and the transmission just stays locked in 3rd.

The fluid level in the transmission should drop a bit when the engine is running, the fluid pump will be pumping fluid through the valve body, torque converter, etc. When you stop the engine, some of the fluid drains back to the pan, thus incresing the level.

Another quick and easy, but messy, check for a failed pump or torque converter is to remove the hose from the cooler and start the engine for a couple of seconds, it should spit fluid out the open hose if the pump is working.

 

It won't throw a code, the only sensors in the transmission are fluid temperature and a revolution sensor, there are no fluid pressure or level sensors.

Also it will only throw a code on these sensors if the sensor itself is faulty, not if it returns an 'out of spec' reading.

 

Somebody noticed I had 3 trans.-related posts going, so I'm going to move it on over to here.

FYI: I finally just talked to a dealer tech. (after being told Nissan, the manufacturer, prohibits techs from talking to other outside techs. then said they were too busy to deal with me, then refused to take a # and have one call on a pee break, then hung up on me, wow)... What I learned:

1.All VG VE auto trannies in neutral = 50-60psi at idle. This should prove pump works. closer to 200psi when driving

2. Don't splice into line from rad. Must come out of trans. with a special fitting to your guage.

I think just letting fluid spurt out to check may not be wise. 50-60 psi is a lot of press.

 

The pressure at the cooler return line is nothing like 50-60psi, they are telling you to check the pump pressure at the test port on the top of the transmission, which is straight off the pump, and this is where it is 50+ psi. the cooler line is just the path the fluid takes as it drains off all components, on it's way back to the pan/sump, and would be lucky to be 5psi.
Removing the cooler line and starting the engine is the way to do a 'home version' transmission flush, which I have done before and can confirm the fluid does not spray across the room.
However, if you have access to the required test components to check the pressure, this would be by far the best way to check. But the fluid pressure can vary significantly depending on a lot of thigs (idle speed, gear selected, fluid temperature, fluid type), but at least you can confirm the fluid pump is actually working.

 

Sonicii!!

Thank you for following my posts. Wait until I tell the G.F. that i have somebody from Australia helping me troubleshoot this thing! OK, so I have no test equip. of which you and the Nissan tech. told me about. I DO however have the guage I just I checked my fuel pressure on my '76 BMW 2002 this week (3.2psi for mech. fuel pump. I think I can go up to 30 psi. on it)

So, I CAN go into the line off the trans. cooler with my vac. guage and as long as I can get at least 5psi off that line I can confirm that the trans pump is OK? Keep in mind... the eng. runs, and will warm up, but I have NO GEARS (no 1,2, D, overdrive or reverse. Park works GREAT though )

 

IMO you are trying to read the "best case scenario" from a measurement that cannot even guarantee that when a tranny is known to still be good and still shifts good.

You keep missing the important bits Sonicii stated here in this thread and I also mentioned in your other thread ................ ie
Without pulling the box and actually seeing what's wrong imo you are looking for a poor placebo only with any pressure measurement ...................... and on top of that, if you fiddle around long enough with the box as it is, you have a good chance of circulating rubbish causing a major disaster by forcing metal bits into unknown places when a "minor" mechanical failure (that could possibly be sorted on an individual basis) was all that originally needed attention.

 

You can tell her that it is more than just Australia and the U.S. It is global!

 

Of course.. there are may different possibilities. But based on the symptoms, the main suspects are the torque converter spline, or the fluid pump. By checking the line pressure, or fluid flow from the cooler line, we can at least say 'yes it is most likely one of these causes' or 'no, it's something else'.

Gerg - if you measure pressure on the cooler line, you still can't really say the fluid pump is fine, only that it is at lease partially working, but you will be able to rule out a stripped TC spline, or a totally failed fluid pump.
Personally, my money is on the spline, and if that is the case, you will get no fluid pressure at all.
But as LvR implied, if you want to know exactly what the fault is ASAP, then the best way is to remove and strip the transmission. However, this is also the most expensive diagnostic method.