2014 Quest SV Transmission Failure (P01778, P0746)

[siny240sx]

Hello Quest lovers,

I currently have 137k miles on my 2014 Nissan Quest SV.

- Trans: RE0F09B (aka JF010E)
- Engine: VQ35 (DE)

On January 11th, I was making a U-turn on a quiet street and my van stalled, and I got a code:

- P0746 - Powertrain - Pressure Control Solenoid "A" Performance or Stuck

I saved the code, cleared it, and have had no issues since. Nothing has been done to a car then.

In April, I went to Florida. The trip was about 1000 miles. Going there was fine, but on the way back, the CEL came on and the car lost power. When I pulled over and read the code, it was:

- P1778 - Powertrain (which according to the manual points to STEP MOTOR

I let the transmission cool down and continued driving slowly. In such a way, stopping every 150-200 miles and let the transmission to cool down, I got home to NYC.

Firstly, I am planning to change the CVT fluid and see where that gonna take me. Most likely, I will not change the Filter. But will clean and reuse the old one.
I'll probably replace the Step Motor as well while I'm there. What brand would you recommend?

A friend of mine told me that he changed the CVT fluid, and it stopped his Altima's transmission from slipping.
He also suggested that Amsoil CVT is much better than Nissan's. What do you think?

Thank you in advance!

[VStar650CL]

1) Replacing the stepper is a waste, that's never the issue. The stepper's job is to work a hydraulic valve, and the hydraulics are always the problem.
2) 137K is a very typical mileage for the fluid to die on an '09B which has never been serviced. CVT's have an extremely simple equation because of the metal-on-metal belt and pulleys: WHEN THE FLUID DIES, THE CVT WILL DIE WITH IT. Change that s#it.
3) AMSoil is better than NS3 in almost every specification.

[siny240sx]

1) Replacing the stepper is a waste, that's never the issue. The stepper's job is to work a hydraulic valve, and the hydraulics are always the problem.
2) 137K is a very typical mileage for the fluid to die on an '09B which has never been serviced. CVT's have an extremely simple equation because of the metal-on-metal belt and pulleys: WHEN THE FLUID DIES, THE CVT WILL DIE WITH IT. Change that s#it.
3) AMSoil is better than NS3 in almost every specification.

Thanks VStar650CL,

Ordered 7 Qts of AMSOIL 100% Synthetic CVT Fluid, Gasket and Filter...

Just drain, clean the filter, and fill whatever amount drained?

Thanks again!

[VStar650CL]

Old CVT's don't have issues with making "ATF soup" like regular A/T's, simply because there's almost no clutch material to make soup. But they do get varnish buildup, and a change will only void about half the old fluid. My advice under these circumstances is to change it twice. The detergent in the initial fresh fluid will scrub all the varnish loose after 1000 miles or so. Then change it again, that will void half of the varnish and give you 75% fresh fluid. After that you can go on a regular 30K schedule.

[siny240sx]

Old CVT's don't have issues with making "ATF soup" like regular A/T's, simply because there's almost no clutch material to make soup. But they do get varnish buildup, and a change will only void about half the old fluid. My advice under these circumstances is to change it twice. The detergent in the initial fresh fluid will scrub all the varnish loose after 1000 miles or so. Then change it again, that will void half of the varnish and give you 75% fresh fluid. After that you can go on a regular 30K schedule.

Thanks,

Ive heard that theory before. Definitely will do.
FIll whatever amount drained?

[VStar650CL]

Yep, unless you plan to drop the pan. For a simple spill-and-fill, do it cold and replace exactly what you remove.

[siny240sx]

Yep, unless you plan to drop the pan. For a simple spill-and-fill, do it cold and replace exactly what you remove.

That's exactly what I was going to do. Drop the pan. Clean it all and put it back on with a new Gasket and new (or clean) Filter.

Is there a difference in the amount of fluid if I remove the pan? How come?
The drain plug is on the bottom anyway...

[VStar650CL]

Then wait until the second change to drop the pan, so you're cleaning out a little more varnish. Dropping the pan always voids about 1/2 quart more fluid than a spill-and-fill, but if you do it cold and you can catch all of it then you can still refill the same amount. However, a pan drop can be messy if there are any slips. Familiarize yourself with the leveling plug method in case you need it. On a unit which hasn't been serviced, expect to find a thick layer of black junk in the bottom of the pan as well as a lot of fine shavings on the magnets. That's all normal, you just don't want to see any metal chunks.

[siny240sx]

Then wait until the second change to drop the pan, so you're cleaning out a little more varnish. Dropping the pan always voids about 1/2 quart more fluid than a spill-and-fill, but if you do it cold and you can catch all of it then you can still refill the same amount. However, a pan drop can be messy if there are any slips. Familiarize yourself with the leveling plug method in case you need it. On a unit which hasn't been serviced, expect to find a thick layer of black junk in the bottom of the pan as well as a lot of fine shavings on the magnets. That's all normal, you just don't want to see any metal chunks.

Thanks VStar650CL,
I'm kinda familiar with what to expect as I did an ATF change on my E39 at 261k two years ago.
Then it was just a preventive measure. No symptoms like now...

So either way (drop or not), fill whatever amount drained?
Hopefully, this job will do the trick...

[VStar650CL]

So either way (drop or not), fill whatever amount drained?

Yep. The only time you really need to use the leveling plug is when you have a leak and the proper level becomes an unknown quantity.

[siny240sx]

Hello guys, VStar650CL,

Sorry for the delay with my response.
Wow, it's been 2 weeks...

Anyway, last Sunday I did the job at 138001. I dropped the pan.
I had only 7 of 1L bottles of AMSOIL, so when I drained 7.1L of fluid, I added all 7 bottles of AMSOIL plus 200ML of NISSAN's NS-2 CVT.

Unfortunately, it did NOT do the Magic Trick I was hoping for. It looks like things are getting worse and worse.

In the beginning, it was okay — I would say promising — but now it is out of hand.
It shudders a LOT. Basically, with every touch of the accelerator.
A couple of times after it badly shuddered, it stalled.

Thank God, my work is only 2 miles away. Otherwise, I would not be able to use this car.
Every time it stalls, it throws the same codes:

- P0746 - Powertrain - Pressure Control Solenoid "A" Performance or Stuck
- P1778 - Powertrain

So I've been thinking...

Since it's pointing to the Solenoid "A" (P0746) and Step Motor (P1778), maybe it would be a good idea to replace them and forget it?
Or do you think the fact that it shudders a lot is already beyond that?

Another question is where to get those parts? Ebay? Amazon? Any specific store? Specific Brand?

Thank you in advance,
siny240sx

[VStar650CL]

If the belt is slipping with a full load of fresh fluid, the only thing which might help is a new Valve Body. From the sound of things there's a good chance your belt is damaged, so if you were a customer, I'd be recommending a borescope inspection before throwing any parts at it. The '09B's have a segmented belt similar to the '10A/'10D, so although Nissan never published a bulletin for them, the '10D bulletin has excellent pics of what to look for:
https://static.nhtsa.gov/odi/tsbs/2019/ ... 8-0001.pdf

If you do find belt damage, don't throw money and time at it, it's done.

[siny240sx]

If the belt is slipping with a full load of fresh fluid, the only thing which might help is a new Valve Body. From the sound of things there's a good chance your belt is damaged, so if you were a customer, I'd be recommending a borescope inspection before throwing any parts at it. The '09B's have a segmented belt similar to the '10A/'10D, so although Nissan never published a bulletin for them, the '10D bulletin has excellent pics of what to look for:
https://static.nhtsa.gov/odi/tsbs/2019/ ... 8-0001.pdf

If you do find belt damage, don't throw money and time at it, it's done.

Thanks for the advice,

I guess I could do that when I was changing the fluid. Not so sure. Sounds like PITA task.
I wonder what my local shop gonna tell me if I ask them to do it

Could either (or both) Solenoid "A" (P0746) or Stepper Motor (P1778) be causing the shudder?
Should I try replacing them? Or is it definitely a bad belt?

[VStar650CL]

Both of those codes are "derived" from the TCM watching the input versus output ratio and detecting that the transmission isn't in the right "gear" for what's being commanded. Neither one is a hard code. So no, it positively won't help anything to replace the stepper, and you can't replace individual solenoids without screwing up the IP values. That's why you replace the whole VB.

So your issue is one of three things:
1) Belt damage. Follow the bulletin guidelines. If there is damage, don't try to fix anything, the unit is trash.
2) Worn out pump. Get CVTz50 and see what your line pressure and target line pressure read. If the actual falls way below the target while trying to drive, your pump is shot. Same deal, if that's the case, it isn't worth fixing.
3) Worn out VB. If (and only if) the belt and LP are both good, then a new VB will probably fix you up. You'll also need CVTz50 for that, to load the IP calibration data from the new VB into the TCM.

[siny240sx]

Both of those codes are "derived" from the TCM watching the input versus output ratio and detecting that the transmission isn't in the right "gear" for what's being commanded. Neither one is a hard code. So no, it positively won't help anything to replace the stepper, and you can't replace individual solenoids without screwing up the IP values. That's why you replace the whole VB.

So your issue is one of three things:
1) Belt damage. Follow the bulletin guidelines. If there is damage, don't try to fix anything, the unit is trash.
2) Worn out pump. Get CVTz50 and see what your line pressure and target line pressure read. If the actual falls way below the target while trying to drive, your pump is shot. Same deal, if that's the case, it isn't worth fixing.
3) Worn out VB. If (and only if) the belt and LP are both good, then a new VB will probably fix you up. You'll also need CVTz50 for that, to load the IP calibration data from the new VB into the TCM.

Thanks,

Currently, I drained the fluid, dropped the Pan, removed the Filter and about to see how to remove the Valve Body.
This time, I drained only (4.75L ???), and I see many more shavings.

[VStar650CL]

Those shavings are probably coming from the belt, from all the slippage and judder you were getting. I'm not real hopeful about what the borescope will show you.

[siny240sx]

Those shavings are probably coming from the belt, from all the slippage and judder you were getting. I'm not real hopeful about what the borescope will show you.

Thanks again VStar650CL,

Ok. Sorry for the delay. I was waiting for a borescope. Finally, I got it. Here are a few pics:

Thank you in advance,
siny240sx

[VStar650CL]

Oh, yuck. Those striations along the edge are all slip marks, that's where the shavings came from. Sadly, she gone.

[VStar650CL]

For the benefit of others looking on, these are pics from the '10D bulletin. The green one is how that belt should look, the red one is how the OP's belt looks (but worse).