66RFE P0731 after rebuild

[Dodgedummy]

hello I need some help. I’m a transmission builder from Michigan working on a customers 2012 Ram 5.7 66RFE. I rebuilt the transmission and am getting code p0731. I swapped the solenoid block and used the correct range sensor. The vehicle will accelerate to 5mph then just revs. Reverse is fine. Doesn’t not shift manually. Works fine in 4LOW. Will go down the road no issues but 2wd and 4LOCK the vehicle doesn’t wanna move. When I rebuilt the transmission everything was done properly did not change anything except what is require during basic overhaul. The shaft isn’t broken. The UD spring is in good shape. All molded pistons were replaced. The correct thickness frictions and steels were used. All 5 check balls in the valve body. No broken accumulator springs. I changed the input and output speed sensors and well as the transducer. I removed the trans again to check my work and didn’t skip a beat. Also reading the scanner data it has shift protocol of an 65rfe it goes into second prime. 4LOW doesn’t shift into 6th did a vin look up to confirm it’s a 66RFE. And the trans is an actual 66RFE Any advice would greatly be appreciated. Btw I apologize for posting about gas when this is diesel forum but I really need help customer is irate I’ve had his vehicle for 2 weeks can’t figure it out

 

[mtofell]

Double and triple check the valve body.... that's a super-common problem with the 66rfe.

 

[Sherman Bird]

Double and triple check the valve body.... that's a super-common problem with the 66rfe.

Transgo shift kit.

 

[Burla]

What was the reason for the original build? Kind of a risk rebuilding the VB, you cant try and toss old one back on. Have no idea what would cause 2wd/4wd but allow 4low to shift. If you have the old solenoid pack I would throw that on now. Sounds like tcm or solenoid, not hydraulic but brain type thing. You got a new solenoid pack?

 

[huntergreen]

Burla is correct, get a new VB with the solenoid pack.