2015 Duramax 2500hd High Country Allison Transmission down shifting to

[Ken Butera]

Hi Everyone, I'm new to this and need some advice. I have a 2015 Duramax 2500hd with Allison transmission. It was down shifting into first very hard. I toke it in to Nash Chevrolet for service. They had tech take for a ride and said they felt it but could not get transmission warm enough to check fluid. It was low in cold at 158 degrees so I went into parts and bought quart of fluid and put it in. Now the level is at hot. That was around 5000 miles. Now at 8991 the transmission is doing it again at weird times when coming to a stop and third shifting around 50 miles an hour is sloppie shifting with a bump when shifting. I toke it into Hendricks Chevrolet in Buford Ga. Today 5-27-16 and they said they didn't have time. So many left and called Gm to get case number and tell them what it was doing and I was heading to Nash Chevrolet. I get there and they tell me after listing to me they are to busy to look at it ( why have a warranty) I called back to Gm and the girl set me up to go to Hendricks Chevrolet in Duluth Ga and to ask for Justin. I get there ask for Justin , he tells me no one called from Gm and gets manager David Carter and he tells me they can't service or look at it today. So if there is any Gm people on here , is this the way you do business. Does any one else know what's wrong or having same issues. Thanks ken

[hollywoodsle]

bro make an appointment. you can't just show up somewhere with a possible major issue and expect them to bump everyone else for you

[Colossus]

Ditto. Make an appointment. It is not practical or customary to just show up and expect them to take their transmission tech off of an already in-progress job. However- I do think it was very unprofessional of GM Customer Care to have not called the service department ahead of time. They owe you an apology.

[SouthpawHD]

Yep, you need to make an appointment.

 

And maybe GM did call Justin but Justin was so busy, they left him a message and he didn't get to it.... Just sayin, all sorts of moving parts here. Just give it some time for all parties to communicate.

[matt123]

Dealing with dealerships is never fun, no matter the brand. But any decent dealership would should've been able to get someone to at least go on a quick test drive or set you up a appointment within the next few days for a quick look at it.

 

I think 158 degrees is plenty warm and considered a normal temperature. I'd be very leery of any "tech" saying he couldn't the transmission warm enough to check. Fluid level should be in "hot" range on the dipstick.

 

I have no clue as to why its shifting hard but hopefully it turns out to be nothing major.

[JRKRACE]

Mine will downshift a little hard when I'm in regen.......

[Ken Butera]

How do you know when truck is in regen? Thanks for taking the time to comment.

[Whiteduramax]

Not sure if I have this problem with my 2015 HD 2500 however my truck occasionally shift/brakes or something real hard when I am coming to a stop. The first time it happened I thought I hit something. I actually got out and looked. Anyhow when it does it, it will do it about 3 consecutive times. It happens at the point of almost coming to a stop and it hits real hard and very sudden. Dealer has no idea what it is. I know when it does it and I pull into my garage it smells nasty.

[JRKRACE]

The nasty smell is the regen...along with an elevated idle...

[levi59912]

My truck started doing the same thing tonight. Is this something common while in regeneration mode? I can also smell a little soot smell in cab, so I'm guessing my truck is in regeneration mode.

[Colossus]

That is correct. You are in regen. My 08 and sometimes even my 2012 can feel like it jerks a little when coming to a stop or taking off from a stop. Only happens in regen. Normal as far as I can tell.

[Nick17]

Hi Everyone, I'm new to this and need some advice. I have a 2015 Duramax 2500hd with Allison transmission. It was down shifting into first very hard. I toke it in to Nash Chevrolet for service. They had tech take for a ride and said they felt it but could not get transmission warm enough to check fluid. It was low in cold at 158 degrees so I went into parts and bought quart of fluid and put it in. Now the level is at hot. That was around 5000 miles. Now at 8991 the transmission is doing it again at weird times when coming to a stop and third shifting around 50 miles an hour is sloppie shifting with a bump when shifting. I toke it into Hendricks Chevrolet in Buford Ga. Today 5-27-16 and they said they didn't have time. So many left and called Gm to get case number and tell them what it was doing and I was heading to Nash Chevrolet. I get there and they tell me after listing to me they are to busy to look at it ( why have a warranty) I called back to Gm and the girl set me up to go to Hendricks Chevrolet in Duluth Ga and to ask for Justin. I get there ask for Justin , he tells me no one called from Gm and gets manager David Carter and he tells me they can't service or look at it today. So if there is any Gm people on here , is this the way you do business. Does any one else know what's wrong or having same issues. Thanks ken

i work at a gm dealer and in any kind of transmission the fluid is supposed to be in cold on the dip stick when the trans warms it goes to hot thats why its there if you over fill it will start dumping out of the vent tube there is over 10 qs in that trans. i have only worked one allison trans and there was a valve body issue