2018 duramax Denali transmission jolting

[Jbetler]

I was towing my Honda 700-4 home on Sunday and as I started to go up a hill my truck jolted 4 times like the tires were locking up. Bap-bap-bap-bap and then every other time I would go up a hill and give it the gas too fast it would do it again. I think my transmission is slipping, only has 36,000 miles. Ye ole Allison shouldn’t be doing this. Especially just pulling a little side by side. Anyone else have this problem. Thanks in advance. James

[DmaxMaverick]

Welcome aboard!

First things first: 2 years and 36K on the clock, this is a warranty issue. Put the least amount of miles on it until you get it to a dealer and document the issue. It may be a powertrain issue not covered by the extended Diesel engine warranty, so time/miles is very important. The PCM performance history will only be stored for a short period, and you want that condition to be read before it vaporizes.

That said, if the tranny is really slipping, the SES lamp should be on (with corresponding DTC's stored), and it should be in Limp mode (reduced power and gear range) at least temporarily. Read the codes, and work it from there.

[Jbetler]

Thanks a bunch. There is no lights on and no limping. When I took off prior to this it would **** and get but now it stutters and then goes. I am afraid to get on it like I used to pulling out of a stop sign, just not knowing what it would do but something definitely is wrong. I shall call the dealer

[DmaxMaverick]

There's definitely something going on with it. Stuttering and no SES or PCM complaints is curious. Good luck with the dealer.