Car is a Maxima SE 2000 with Aut. trans.

Symptoms: Car has erratic transmission operation. Car won't shift in 3rd and 4th gear. 4000rpm at 75km/h, if you push the o/d button and take it of, the transmission slips and engine rev to cutoff. Engine seams to work properly, and idle is good. Shifts from reverse, first to second gear is smooth. But will rev up or get back to first gear without behing needed or with any additionnal throttle.

What I've done so far:
-6 months ago:
Replaced the MAF sensor after an erratic throttle response episode - this was before the transmission problems started occuring. I also cleaned the throttle body at that time and replaced air filter.

-This weekend:
-I adjusted the TPS properly, to get 500ohms closed, and 4000ohms with WOT. Operation is smooth and gradual and you increase throttle.
-Took off the tranny oil pan, took off the solenoids and cleaned everything including the debris magnets at the bottom of the pan. Made the solenoids operate with current and made them "click" properly by cleaning them with compressed air. Tested - works fine. Reinstalled.
-Took out the TCM, opened it, checked for cracks, cold soldering issues and for fried components, board is perfect from the exterior, no issue. Reinstalled.
-Took a look at the crank position sensor under the engine, near the oil pan. Took harness off (was hard to get out), inside of the connector looks clean, no debris or grease. Didn't pull the sensor off tought...

I also did a scan, found the following codes:

-P0744 Torque Converter Clutch, Solenoid Circuit Intermittent
-P1446 Evap canister problem
-P0174 - too lean - bank 2 (I think this is normal as I have a small hole in the flexible part of the exhaust, just before the cat...)

I erased the codes after I had worked on the car, and went for a test drive. Car still did the exact same thing. Only the EVAp code came back (haven't check that yet).

What I suspect now:
-bad revolution sensor
-bad crack position sensor (don't know if it can affect the transmission operation like that tought...)
-TCM and/or ECM need a reflash / reprogram (considering I adjusted the TPS, changed MAF a while back etc...)

Let's hear what you guys think!

Thx

 

the P0744 is why the transmission is not shifting properly. I'm not an auto transmission guy so I don't know how to fix it. But that is a serious problem.

 

Torque converter and solenoids works properly. I cleaned 2 solenoids who probably had metal debris in them and were sticking and hard/impossible to operate. But the transmission did the exact same thing after that anyway... But again, this doesn't feel like a machanical problem, it's a problem who came up one day, not over some period of time. I strongly suspect the revolution sensor, or the TCM....

 

Trying to get the correct part, I see a lot of conflicting info on both the TCM and the revolution (speed) sensor.

Part #s seams to overlap on those revolution sensor at some point... Very hard to tell which one I need exactly... Some even refer to the tire size... stating that it fits only on 16" wheels... mine came with 17" standard...

On the TCM, there's a lot of different #s on the tags too... "M7" being the most common... there's also "MG"...

Any guidance would be apreciated.

Thx

 

How many miles on the car ? Sounds like the band and high (3-4)clutch pack is having issue. What if you manually up shift it ?

 

Car has 190K km (118K miles).

Can you elaborate on the band and clutch pack ? And would they cause the weird unwanted downshift at low speed?

Car shift somewhat fine from 1rst to 2nd, so manualy shifting doesn't change anything... But in D4, it doesn't get past 2nd.

 

The band is for 2nd gear, if the band is smoked then you will have problem with 2nd gear. You can try tighten the band a little and see if it help.
http://img684.imageshack.us/img684/2641/photo31z.jpg

 

Second gear is the one who works best at the moment (unfortunately!). Actualy, I just brough the car back from the cotage tonight - so I just did 40 miles in 2nd gear!

Man I really tought I had found my problem tonight when I took off the splash guard behind the left front wheel, to get access to the revolution sensor on the tanny... There was a ground wire with a plug at the end hanging loose just beside the suspension. This wire was connected to a terminal under a bolt, on the side of the transmission housing. I put a new terminal on and re-installed it... Erased the code via OBDII, disconnected the battery for 30 minutes... then went for a test drive... same thing again... no 3rd gear...

Couple things I noted on the way back... Trans just don't want to get into 3rd. (and 4th off course...). When I'm in 2nd gear, if I take the O/D off, the transmission disengage and the engine revs... Putting it back ON locks 2nd gear properly again.

When going down hill, if I let the trans in D4, the rpm will just fall back to +/-1000RPM. If I take off the O/D then, there's a little bit of compression/decelaration from the engine which rev up a little...

One other thing, I checked the revolution sensor before bringing the car back tonight - there was some sort of oil on it and very small metal residue (like on the transmission pan magnets...). I cleaned it and reinstaled.

 

When you drop the pan, is there any metal on the magnet ?

 

Yes, there was fine metal particules on both magnets.

 

If there is excessive metal in the pan, the transmission is toast.

 

Hard to tell what is excessive and what's not. There were no big chunks of metal in the pan. The biggest ones I found where the size of a ball point pen tip... And there was not a lot. The rest was like grey powder more or less and it sticked to the magnets.

Seeing the way the transmission shift from 1rst to 2nd, and when the torque converter re-engage the 2nd at high speeds, it operates too smoothly to be fried in my opinion.

Plus, this "no 3rd gear" thing happened all of a sudden. Never missed a beat before the day it happened...

Really weird....

One question, if the TCM or ECM have never been re-flashed or updated since 2003 (for sure), is it possible that they could be reflashed and updated to a newer firmware? Or after replacing the MAF, taken off the TPS, cleaning the T. body and re-installing/re-adjusting the TPS, would it be possible that the ECM/TCM would need to the reseted so they can "re-learn" the data coming from those sensors ?

 

There should be other way of reset the ECM, i have access to a scanner that could reset to factory setting, but usually i just disconnected to battery, if the SES light still on then i just clear codes with scanner and re-drive it.
A good good working transmission should have no metal in the pan. The metal partical is generate from burnt or broken parts from inside of the transmission, just very fine powder metal partical can hang up the valves inside the valve body and can cause bad things. I could be wrong, but you can take the car to a reputable transmission shop and have them diagnose the trans to see if it's internal or external problem, the cost is around $40 or so.

 

Went to the Nissan dealer yerterday, they got the P0744 code from the TCM and ECM aparently... so this "kind of" confirm that it's either the solenoids, or the torque converter... I just purshased a used trans., so I'll try to swap the solenoid pack first, see what happens... If not, I'll drop the other tranny in...

 

The torque converter has nothing to do with no 3rd or 4th gear, you have more than 1 problem. Good luck with the used transmission.

 

Tonight I took the complete valve body that was on the used transmission that I bought and installed it in the car. I also put in a new oil filter and swapped the rev sensor too while at it...

Transmission does the exact same thing as before

Either the TCM is fried or it's a mecanical problem in the transmission...

The only thing I find weird is that the transmission still goes from 2nd to 1rst whitout any reason, as if it had no reference of speed or "power demand"... If it wasn't for that, I'd bet on a mecanical trans. problem...

 

This morning, I was trying to find the cause of my low voltage... I cleaned both battery post and the terminals... Still voltage is in the high 11V range and now I have the battery sign lit up in the dash...

I'll try to get an output reading on the alternator tomorrow...

I also did a lot of tests on the TCM. All voltage or ohm reading seams to be within spec, expect one. The signal from the "Vehicule speed sensor" on pin #40.

This is what they say:

-Check voltage between TCM terminal 40 and ground while driving at 2 to 3 km/h (1 to 2 MPH) for 1 m (3 ft) or more.

Voltage varies between less than 1V and more than 4.5V.


I tested mine and it jump all over the place. I get all sorts of readings ranging from 0 to 5V. (2.1V, 3.5V, 3.65V etc...). They say it should either be under 1V, or over 4.5V and mine doesn't do that... Even when the car is stopped, it still show 4.5 or 4.6 volts readings! (??)

Now when they say DTC VEHICLE SPEED SENSOR·MTR, what part are they reffering to? The transmission rev sensor, abs sensor, speed sensor in the speedo cluster ???

Again, thx for the help.

 

VSS location should be on top of the transmission's differential.

 

Does the 2000's have a VSS at all?

If it was deffective, would the speedo be erratic ? (because it's not).

 

00 Should have a VSS on top diff, later on they plugged it up. I'm not sure if the speedometer is operating by the VSS or not, because you do have the wheel speed sensor by the axle also.

 

Did you figure out what the problem is? I'm having the same problem with my 03?

 

No, haven't had a single minute since last week to look at the car...

I went by my spare tranny today and looked at it, seams to be a sensor on the transmission that could be the VSS (Still not 100% sure there is one...).

What makes me doubt that it could be the issue is that my speedo works fine. Altought the problem might be between the speedo and the TCM/ECM...

 

I parked the car all summer. Now ,I'm back on it, and I'll try to find the problem...

Anyone of you guys had any luck with a similar problem?

 

A quick update.

I replaced the battery and now I get a very good voltage reading from the alt and bat. 14.7V +

Went for a quick drive, car does the same thing.

One question: when the engine is warm, if I give it some throttle (anywhere from 10% up to 50% I'd say), the rpm will over around 1600-1700rpm as if it was in cutoff mode. Going up to 1700RPM then quickly back to 1600rpm while the ignition seams to momentarely cut, then back and forth over and over again...

What is that? I suspect the closed throttle position sensor but might be wrong... What do you guys think?