Hello All,2018 Ram 2500 6.4L Hemi with 4.10. Heading back from camping today, tow/haul mode on, after a long hill my truck suddenly left "D" and locked itself in 4th gear. I was on the highway doing about 65 so it was not that big of a deal, but I could not make it go back to D, upshift, downshift, nothing. Kept driving 2 miles until the next exit which happened to be mine. Seemed fine until I came to a light in town. It never left 4th. Needless to say it was not pretty trying to start from stop with 10k Lbs trailer in 4th gear. Got it going just to clear the intersection and pulled over where I could. Just as I pulled over a light said "Transmission is too hot". I let it idle for about 5 minutes hoping the trans cooler would cool it. After that 5 minutes the light went off but I was still stuck in 4th. Turned the truck off and re-started and all seemed fine for about 4 miles and then the same thing. I was about 10 miles from home thankfully so I limped home, shutting down and restarting at each light. Almost home the engine light went on. I am in warranty so I'll take it in this week but curious if anyone has seen this issue. Truck pulls the trailer great and never had an issue. It does scream sometimes pulling long hills but never felt like it was struggling. Also strange that when I re-start it shifts fine until it locks in 4th again after 5-10 min. Any thoughts? Thanks!

My only thought is... its good you have warranty!. So much for the ZF 8 spd and you have my sympathy… Really. It sounds very expensive, and hopefully only for FCA. Craig

I can't say why it would lock in forth, but bet the overheat was because of the converter friction starting the load in 4th.

Well, the basics are:Did you have enough fluid in it?Do you service your transmission regularly including fluid and filter?Do you have a transmission temperature gauge? What was it reading?It could be a computer glitch, could be a trans problem, could be an actual overheat due to outside circumstances.

That is a symptom of clutch pack failure. Shut down and restart can reset the system temporarily.

KD4UPL wrote:Well, the basics are:Did you have enough fluid in it?Do you service your transmission regularly including fluid and filter?Do you have a transmission temperature gauge? What was it reading?It could be a computer glitch, could be a trans problem, could be an actual overheat due to outside circumstances.Well the basics are no dipstick, 2018 truck not likely to need service unless it’s got over 60k miles (the 2500 HP8 interval I believe).

Tranny overheated | Good Sam Community

ppine
Explorer II
Nov 09, 2020
People are asking the right questions, except for one.
How much weight are you towing? Burning up a transmission is the most common thing that happens with too much trailer and not enough truck.
rhagfo
Explorer III
Nov 09, 2020
KD4UPL wrote:
Well, the basics are:
Did you have enough fluid in it?
Do you service your transmission regularly including fluid and filter?
Do you have a transmission temperature gauge? What was it reading?
It could be a computer glitch, could be a trans problem, could be an actual overheat due to outside circumstances.

Well depending on trim level for the instrument cluster the engine and trans temperature should be available on the instrument cluster.

If still under warranty should be somewhat low miles 2018 6.4 with 4.10's, 10,000# should be well within tow ratings.

Differently need a bit more information.

Weather when this happened?

OP states after long hill, how long, and how steep, how fast were you climbing?

Can and did you check trans and engine temp while climbing that hill?

Have you checked the trans fluid level since this happened, and is it correct?

Have you checked the engine coolant level?

Could be just a faulty sensor sending bad data to the management computer, or a slipping trans.
deltabravo
Nomad
Nov 09, 2020
How many miles on the truck?

I'm guessing that it doesn't have a trans temp gauge, since the OP never posted what the temperature was and only mentioned a dash light turning on.
4x4ord
Explorer III
Nov 09, 2020
Is it low on fluid?
goducks10
Explorer
Nov 09, 2020
C Schomer wrote:
My only thought is... its good you have warranty!. So much for the ZF 8 spd and you have my sympathy… Really. It sounds very expensive, and hopefully only for FCA. Craig

2018 has the 68RFE
Grit_dog
Navigator
Nov 09, 2020
KD4UPL wrote:
Well, the basics are:
Did you have enough fluid in it?
Do you service your transmission regularly including fluid and filter?
Do you have a transmission temperature gauge? What was it reading?
It could be a computer glitch, could be a trans problem, could be an actual overheat due to outside circumstances.

Well the basics are no dipstick, 2018 truck not likely to need service unless it’s got over 60k miles (the 2500 HP8 interval I believe).
bguy
Explorer
Nov 09, 2020
That is a symptom of clutch pack failure. Shut down and restart can reset the system temporarily.
KD4UPL
Explorer
Nov 08, 2020
Well, the basics are:
Did you have enough fluid in it?
Do you service your transmission regularly including fluid and filter?
Do you have a transmission temperature gauge? What was it reading?
It could be a computer glitch, could be a trans problem, could be an actual overheat due to outside circumstances.
JRscooby
Explorer II
Nov 08, 2020
I can't say why it would lock in forth, but bet the overheat was because of the converter friction starting the load in 4th.
C_Schomer
Explorer
Nov 08, 2020
My only thought is... its good you have warranty!. So much for the ZF 8 spd and you have my sympathy… Really. It sounds very expensive, and hopefully only for FCA. Craig

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