68RFE Trans Doesn't Want To Shift When Warm

[Justingz71]

Ok, so a little about the truck: It's a 2015 RAM 2500 Laramie Limited with the 68RFE. 139k miles.

I don't know the mods because I just bought it a month ago, and the dealer I got it from didn't know what had been done to it.

DPF/ def deleted with a 4-inch downpipe back straight pipe.

No tuner came with the truck, so I'm running a mystery tune. I will be getting it tuned by Dr. Diesel as soon as I know that I'm not about to have to replace a tranny.

I can't afford to do both right now.

So this week, I got to take the truck out for its first long trip since I purchased it.

The truck ran fine, shifting mostly smoothly with no shift flare.

However, after about 3 hours of driving (north Georgia mountains, no trailer, and just a backseat load of gear), the truck started acting like it wouldn't shift. 1-2 was fine, but it stayed in 2nd and would not upshift for like a solid ten minutes regardless of the road's incline or how much throttle I gave it.

Eventually, it shifted into 3rd and then again seemed like it wouldn't upshift to 4th.

After about 60 seconds or so, this time-shifted to 5th, then 6th, no problem.

Trying to use the manual shift buttons didn't seem to help.

The truck continued to stay in 2-3-4 for like at least 30 seconds before shifting up while downshifting fine.

We pulled over, went inside some stores, and gave the truck an hour to sit. After the hour, the truck drove much better, with only 1 or 2 shifts delayed for the last 20 minutes of our trip.

Over the next two days, the truck drove fine on short trips around town, but it was the same story when we came home.

After about 3 hours of driving, the truck would stay in gear for a very long time, like 30-45 seconds, before shifting up when going into gears 3-4-5.

Any help in diagnosing my problem would be greatly appreciated.

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[watersupply189]

When was the last time the trans was serviced?

Have you checked the level of the transmission fluid?


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[Justingz71]

When was the last time the trans was serviced?

Have you checked the level of the transmission fluid?

2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

I checked Trans fluid with the truck running in neutral, and it looks good.

Supposedly the trans was serviced, and the clutch was replaced 1 month ago, right before I bought it.

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[nitsuj08]

There’s no way to properly diag.

If possible, I’d take it back to the dealer if you have some sort of lemon law or warranty.

It sounds like it may be a lousy tune; not 100% sure.

These trans are super weird but good with the right stuff.

ive done so much trial and error with my current setup and am dialing it in now.

So feel free to fire more questions.

If I was you and only 2 options were to take it back or carry on with diag, I would purchase a cheap tuner (H&S) with trans tune; that way, you can reflash and be able to monitor pressures and such or something you can hook up to monitor (not necessarily a tuner).

There can be many things, but that might be a cheap start.

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[Justingz71]

I appreciate the suggestions.

I'm mechanically inclined, but this is my first diesel truck, and I have no experience with transmission work.

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[watersupply189]

Keep us updated on what you find out.


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[Justingz71]

Ok, so quick update.

I called the dealer and am taking bit back to them later this week.

I haven't yet because I am a travel nurse and am finishing a contract and haven't been back to the town where I bought the truck yet.

I was driving the truck today trying to get my camper moved. 2 hours total drive and about 8k pounds.

After 1 hour of driving, I lost all gears except 1st and 4th.

Again let the truck sit and cool for 20 mins, and it drove and usually shifted until it got warm again.

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[Corkey]

Thank you for the update, bud.

It sounds like you got an extended warranty, I hope.

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[Acerock]

Did it throw a check engine light and populate any codes?

It almost sounds like you might have a worn valve body.

These have a solenoid switch valve which wears in its bore, causing issues similar to what you describe.

The mileage on your truck coincides with when a lot of these are known to fail. But it should have thrown a code.

Either way, the dealership should be taking care of you.

It most likely doesn't need a new transmission since it holds power and usually behaves when cold.

Hopefully, you'll be back on the road with a new valve body.

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