Kick down 2021 2500 Cummins

[RSA964993]

I was 3 hours into my drive today, towing my enclosed trailer (6000ish lbs between trailer and car in trailer), when this happened. Traffic on I85 from Atlanta to Charlotte became a bit congested, so I slowed down to 65MPH and then highway turned into a gradual incline. Traffic cleared, and I pushed the throttle down which normally means a kick down to a lower gear, and off I go. Instead, there was no kick down. It stayed in the higher gear and SLOWLY accelerated. I floored it. Nothing. I took my foot off the throttle completely, and tried again. No kick down. This went on for about an hour. This continued when the highway leveled out. There were no dash lights, and all readings in the engine info were normal. It felt like the an accelerator pedal wasn’t doing any at all. The speed gradually increased, but no where near what it normally would do. I played with the exhaust brake and the tow/haul toggle and it didn’t make a difference. An hour or so passed and then it went back to normal acceleration. Any ideas what would have caused this? Is this a precursor to something bigger? Thanks. Rob

 

[AH64ID]

I recall this being an issue on 15-17ish HO’s, but only at elevations above 5-6K feet. IIRC it was fixed with software update.

Unfortunately if you can’t reproduce it and it didn’t throw a code there isn’t much that can be done.

 

[RichM752]

In December, I had the same thing happen towing the 5th wheel up a grade. I pulled off the interstate, shut off truck, restarted and all was fine after that. Made an appoiintment to have trucked looked at dealership,they downloaded the latest software and called it a day. Never happened again.

 

[RSA964993]

Thanks for your response. Good to know it is a thing and hasn’t happened again. I was contemplating pulling off and doing a restart but had no idea if I was going to get stranded. It came back almost like it was exiting a limp mode setting. It kicked down much slower than it normally would and acceleration was improving. After that it went back to the way it’s supposed to be. No issues the rest of the trip.

 

[H3LZSN1P3R]

Thanks for your response. Good to know it is a thing and hasn’t happened again. I was contemplating pulling off and doing a restart but had no idea if I was going to get stranded. It came back almost like it was exiting a limp mode setting. It kicked down much slower than it normally would and acceleration was improving. After that it went back to the way it’s supposed to be. No issues the rest of the trip.

Thats an issue i had a couple of times i would just manually make it drop to 5th and be done with it. Then it would not happen or a while.

Since i tuned my truck and trans i have never had that issue and it kicks down very well like they used to with a kick down cable

 

[RSA964993]

Mine actually is tuned (Calibrated Power) and switched between tunes when this was happening. It didn’t make a difference so I concluded it wasn’t anything to do with the tune. I was in light tow mode and put it in neutral and then selected hit heavy tow. How did you manually make it select the lower gear? Thanks.

 

[H3LZSN1P3R]

Mine actually is tuned (Calibrated Power) and switched between tunes when this was happening. It didn’t make a difference so I concluded it wasn’t anything to do with the tune. I was in light tow mode and put it in neutral and then selected hit heavy tow. How did you manually make it select the lower gear? Thanks.

Hit the gear - on the steering wheel…. Do you have trans tuning? If so try the medium shift pattern trans tune its so much better than stock

 

[RSA964993]

I thought that was a low gear thing so didn’t even consider it. Appreciate that information. I believe only my ECU is tuned. I don’t have one specific to the transmission. I thought the tune I have addressed both engine and transmission. Not sure though.

 

[GPurcell01]

Sometimes the 68rfe will get stuck in a gear and will sit there. Happened to my neighbor towing his 5th wheel. I believe it took until he got off the highway and stopped for fuel before it cleared itself.

 

[H3LZSN1P3R]

I thought that was a low gear thing so didn’t even consider it. Appreciate that information. I believe only my ECU is tuned. I don’t have one specific to the transmission. I thought the tune I have addressed both engine and transmission. Not sure though.

If you have engine tuning you Absolutely should have trans tuning with the 68RFE with just tuning the trans can hold 550RWHP!