66rfe going bad?

[slapshot]

Happy Thanksgiving

I have a 2018 2500 6.4 gas with an 66rfe intermittent transmission issue. 95k on the transmission. Truck shifts awesome around town, getting on the highway when it downshifts occasionally there is a hard shift then the truck gets stuck in maybe 4th gear. I believe it is 4th gear but not positive. Truck only goes from 1st to 4 gear afterwards until the truck is shut off. Once the truck is shut off and restarted it is no longer in limp mode and runs great. It could run great for 1k miles before it happens again or it may happen right away.

It is intermittent. No codes and the transmission fluid has about 25k on full synthetic fluid. I have been told it's anywhere from 5k-8k transmission job. Maybe the transmission is on its way out. Any ideas on possible other solutions? maybe solenoid or valve body?

 

[Burla]

It sounds like solenoid or valve body, and the usual suspects with rfe is you lose over drive first in the VB. It sounds like solenoid, but could be either, most end up being VB see vid. Obviously you will just do both if you opt for dyi. Find a good source for products if you dyi, most of the time anyway you will need a quick learn or dealer flash to go past 4th gear, this is hit or miss here ram forum, sometimes it will work out of box feel lucky? Most of the builds are for the 68, kind of a bad deal they didn't put the 68 in those trucks, 66 is harder to find stuff, info travels from rfe to rfe, but you need to find 66rfe parts. All atf 4 is synthetic.

Have you checked fluid level when hot? Did you use metal threads upgrade for new filters?

Product Overview: ATS 68RFE Valve Body and ATS Co-Pilot

Clint Cannon, President of ATS, describes the inherent weaknesses of the 68RFE (545RFE, too) valve body. This is a comprehensive overview of the numerous pro...

youtu.be

 

[buckeyexx]

I agree sounds like valvebody or solenoid pack. I would do both. Very common issue. They are easy to do if you know how to change fluid then it’s just a few more steps beyond that.

The valvebody for the 68rfe will be the same for the 66rfe. Same with the solenoid pack. No difference in the two at all. And you will need a relearn afterwards. Any decent shop should be able to perform that.

 

[White six four]

Does it go into limp mode if you manually downshift? I got in the habit a while ago to manually downshift if I know it will be needed to speed up or make it up a hill. All in an attempt to make my 66rfe last as long as possible. Along with fluid changes yearly.

 

[Burla]

if you get alpha guys report you can quick learn.

 

[slapshot]

thanks guys. Looks like the valve body swap is pretty simple. The re flash stuff is where it gets tricky. I gotta find a way to test the line pressures first I guess to make sure the thing is worth doing the valve body swap to. Watched a video by randys transmissions. Anyone uses Randys transmission valvebody?

 

[Dusty]

Happy Thanksgiving

I have a 2018 2500 6.4 gas with an 66rfe intermittent transmission issue. 95k on the transmission. Truck shifts awesome around town, getting on the highway when it downshifts occasionally there is a hard shift then the truck gets stuck in maybe 4th gear. I believe it is 4th gear but not positive. Truck only goes from 1st to 4 gear afterwards until the truck is shut off. Once the truck is shut off and restarted it is no longer in limp mode and runs great. It could run great for 1k miles before it happens again or it may happen right away.

It is intermittent. No codes and the transmission fluid has about 25k on full synthetic fluid. I have been told it's anywhere from 5k-8k transmission job. Maybe the transmission is on its way out. Any ideas on possible other solutions? maybe solenoid or valve body?

Although the symptom you describe can be a valvebody issue, I would take a cursory check of the electrical terminals in the transmission connector since this problem is randomly intermittent. Check for green crusties and maybe clean both halves of the connector. Of course, there could be the same issue with the connectors at the PCM.

It would be nice to know where you're located since the type of environment the vehicle operates in can help in troubleshooting.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 123517 miles.

 

[big tom]

Don't know if this applies but my 2016 2500 had a recall on the solenoid pack. It stuck in like 4th gear right before I took it in. Been fine since.