'18 Power wagon 66rfe rebuild won't shift properly

[AKPW 66rfe sucks]

So I went through my 66rfe at 85k miles on my 2018 Power Wagon. Had a heavy tow and it slipped 5th gear which led to eventually rebuilding. I added a Son valve body and all new and upgraded friction plates in as a kit. Also changed the Solenoid pack and all exterior sensors. My issue is after getting the rebuild complete the truck will not hardly move forward. its slow to engage and when it eventually tries to shift it goes into neutral. Every now and then it will grab a gear and move perfectly fine until it tries to shift again. Reverse seems to work just fine. I did a re learn an that seemed to make it even worse. Is there something else I need to do to the PCM or can try to make sure this isn't a computer issue with the new rebuild? I just want to make sure I completely prove the PCM out of the question before I tear this thing apart and look for something else.

Oh and it throws zero codes but will eventually go into "limp mode" and try to shift to 4th.

Does battery life and or fuel level make for a false re learn? It says completed successfully but i read a couple places that these would stop a quick learn from working.

 

[Jeepwalker]

I honestly don't know on the Trans re-learn. Have you downloaded and checked the Service Manual?

How did you handle the main pump? Did you leave it, replace it, clean it? You're sure it was back together properly? It probably only goes one way...but..

Since you replaced the solenoids with new ....does your scanner allow you to run the solenoids through a 'test' routine? Do they seem to be working ok?

Are the fluid pressures reading ok? ..or have you unhooked the radiator line, start ... and let it pump into a bucket for a few seconds, to gauge the flow?..

I'm just thinking out loud. I might be inclined to shoot a few questions out to the valve body outfit tech support. See what they say.

 

[Burla]

Transmission fluid level good? Do a psi test. Test it in every gear and neutral. Did you keep all of the old sensors?

 

[Burla]

Was the solenoid pack white or grey? Same color as the one replaced? There is a thing with check ball numbers and solonoid color, I believe it is if you have 7 check balls with a white solenoid it cant be wrong, if memory serves. Where did you get the VB? I'm not saying this is the issue, usually it will work just wont go past 4 gear if you mess this up, just checking. Even if you replaced exact solenoid pack the VB could have a different number of check balls if it was a replacement.

 

[Jeepwalker]

The idea that it won't legitimately move kind of leads me think that 1st gear solenoid ..wiring to the solenoid (but that would probably throw a code), pressures or the clutch servo (??).

A guy could throw the previous valve body on and see if it works then. I know that would be a PITA.. If I was going to pull the pan again, I'd quadruple check the oil flows first before pulling the fluid. In case you somehow got a defective screw-on filter or somesuch. Then I'd probably put on or swap/test the solenoids and put the previous valve body in. Assuming of course the relearn has occurred. Even if it hasn't...it should still engage tightly I would assume. (??).

There could be a 1-2 servo o-ring that got boogered up in the reassembly process. And that would keep it from engaging.

The service manual should have a discrete method of checking pressures, procedures, to drill down & zero in on the problem. Go to the BOTTOM of the page HERE and keep clicking 'ok' etc and download the FSM, check if there's a good tranny section. Yer probably going to have to take an 'organized' troubleshooting approach on this. Or you might be able to go to the dealer and see if they'll print out the tranny section on a unit repair manual. Or maybe you already have a manual??

Good luck. Let us know what it turns out to be.

 

[62Blazer]

I am not a trans expert, but have been involved in many transmission replacements over the years. Will say that I have never seen the "relearn" procedure cause anywhere near this type of issue. Maybe a few funky shifts but for the most part the vehicles always drive at least reasonably well without the relearn. As mentioned above it really sounds like an o-ring or something got messed up and is not allowing the correct pressures.

 

[AKPW 66rfe sucks]

The reader I am using is saying desired line pressure at 870psi and actual around 845psi. I am not sure what to think of these numbers as they seem way to high to be possible. Also don't know why they wouldn't be throwing a high line pressure code. You all have pushed me further where i was headed in it being a seal issue on one of the switches or pump issue. Solenoid pack was was grey and replaced in kind. I'm just confused on the fact that all these pump or flow issues should be throwing some kind of code to lead me in a direction.
I didn't tear down the pump when i rebuilt it, probably a costly mistake. but it will just add to most likely many more to come. I can still rebuild this transmission 6 more times for the price of having someone else do it.

 

[Burla]

Those are not correct psi, so you replaced the grey solenoid pack with grey, but you also changed the valve body yes? So white would be universal, which is why most shops only use white solenoid packs so I'm told. So this isnt the issue unless you fix the issue and then find you cant get past 4 gear, then it is possible the VB was rebuilt with the 7 check balls and not the 5 you should have, so consider that if you get to that. This is happening because people are just rebuilding rfe valve bodies thinking they are universal, but they arent, which is why most places are ignoring the grey solenoid packs and opting for white. Even if you have the wrong check balls per your application it cant be wrong with the white solenoid pack.

Are you saying your reader is saying you have 845 psi? Something would be stuck in the system. Did you remove sump filter gasket and replace with new gasket? Probably wouldnt be that anyhow even if that went into filter might not create psi that high.

 

[Jeepwalker]

If the tranny worked Ok before, you'd think the pump would still be ok, even if you left it be. I'd swap back the original valve body and look at the solenoids. And ensure your filter isn't a one-in-a-thousand defective unit.

That's the kind of thing that happens to me where I spend hours hunting problems ...and turns out I got a defective basic part.

 

[Burla]

Accumulator piston stuck maybe? Dunno, but is you are 845 psi that valve body needs to be taken off and checked. Your original issue was probably a leak, either in pistons or plate, and then you probably replaced a ton of stuff that was aged but still useful.