66RFE Hard shifts, P0871 = Toast?

EugeneTheTJ

Well-Known Member
Joined
Dec 4, 2010
Location
North Carolina
Truck is a 2017 Power Wagon with 6.4 hemi and 66rfe. 93k miles. Very easy life. Next to no towing, only lightly offroaded, mostly around town and highway miles.

For about the past 8-9 months, I was getting occasional hard shifts from 3 to 4. It got to the point where it was hard enough to chirp tires. Never downshifting, only up.

Took it in to regular mechanic and they could never replicate. About 3-4 weeks ago took to transmission shop on trusted referrals. They thought initially it was likely computer related and suggested a fluid change and relearn. Inspection of fluid indicated nothing in terms of ill wear.

Truck seemed to do a hell of a lot better for a week or two. Then gradually started getting hard (but not as hard) shifts again. They weren't always consistent gears though - either 1-2 or 3-4. Again, no issues downshifting. The other day it was shifting like hell again and I noticed it seemed to be getting stuck in certain gears for too long before shifting up. At one point during this scenario CEL came on yielding code P0871 - OD Pressure Switch Rationality fault.

The next morning, code went away but took it back to same transmission shop. They took a look and said transmission is shot. Still driveable, but needs rebuild or replacement as eventually it will fail entirely. They are confident replacing a valve body or solenoid would not fix it, which I'm not wise enough to agree with or say it's worth a shot.

Rebuild price is over $6k. I don't want a straight up used unit but would be ok with reman from Jasper or similar. Apparently Ram has a backorder on orders through them of over 1,000 units.

Any advice? I'm within spitting distance of paying off so really don't want to trade in and get something new plus the payment that comes with that. Really just focused on best route to fix. Would love suggestions and any commentary on experience with this tranny (or similar like the 68rfe), this code, or rebuild/replace advice. Also, is ruling out valve body/solenoid BS?
 
Did you buy it new? Should still have the 100k powertrain warranty on it from Mopar.

Otherwise get a second opinion. $6k is a pile of cash to toss at it
 
I'd want to see the CVIs. Clutch Volume Indexes. It's a mathematical value indicating each clutch's amount of slipping. If the CVIs are within spec, I doubt you have a clutch/slipping issue. I'd them look into the valve body having a failed and/or leaking SSV.
Used to replace a lot of VB for that issue back in the day.
 
I'd want to see the CVIs. Clutch Volume Indexes. It's a mathematical value indicating each clutch's amount of slipping. If the CVIs are within spec, I doubt you have a clutch/slipping issue. I'd them look into the valve body having a failed and/or leaking SSV.
Used to replace a lot of VB for that issue back in the day.
I'm gonna have my regular mechanic provide his opinion and see if I can get this data from him.

The transmission shop said they thought it was likely one of the drums causing the issue
 
My mechanic also suggested rebuild but is $1k cheaper. Likely to take that route. He said if his scanner can show that data he's happy to provide it but it's a matter of figuring out when they can work me in.
 
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