Interesting... progress with odd trans behavior? (2015 6-speed)

[OmniGLH]

So while certainly not as vocal... I do notice occasional odd behavior with the trans and shifting in my 2015 Sierra 1500 SLT.

 

I was chatting with a friend of mine I know through a local car club, and it turns out he's actually one of the senior techs at a GMC dealer a few towns over. So I've been trying to pay closer attention when the trans does something funny (harsh 2-3 upshift, delayed downshifts, occasional shudders, feels like it gets "stuck" in a lower gear then pops, etc.) and relaying it back to him.

 

He hit me up the other day and told me to disable grade braking, and let him know how the truck feels.

 

To disable grade braking, you hold the Tow/Haul button down for a few seconds, then release it. (This is NOT "hill descent control"). You get a popup on the DIC that says it's been disabled.

 

It definitely makes a difference. I was concerned it was just placebo effect... but he confirmed my observations are what they expect to see. Much smoother shifting. No more "confused" feeling by the trans. No more odd clunks.

 

He told me "they" think they're narrowing in on the problem. I assume he's talking about GM/factory. Says one of his co-workers (also a tech) is a big truck nerd and has been trying to sort this stuff out with his own truck.

 

Give it a shot. Let me know if you feel the same thing I do (for my own curiosity's sake).

 

 

[hirdlej]

I abso-freaking-lutely hate grade braking. I like my vehicles to coast when I let off the gas. I disable this feature every time I get in my truck. I wish it were selectable and was off by default. It kills MPG as when you let off the gas it starts slowing your truck down for you. If I let off the gas it's for a reason, to coast. If I want to slow down that's what the big pedal is for. ;)

[The Mad Veteran]

Interesting! I'll have to keep this in mind when my truck is finally delivered. It's king of weird they would have this activated at all time and sounds like they need to fix this. Maybe they will post a recall and update the software later on to have this turned off when you get in and activate it when you want.... how it should be.

 

Edit:

Anyone have the same issue with the 2016 6 speed?

[lawnboy-5247]

Double post

[lawnboy-5247]

Thats intersting my 2014 almost never grade brakes.

[ewbldavis]

Mine isn't active all the time. Only when in tow/haul mode usually.

 

I think it drives better in tow/haul mode, and actually have noticed an improvement over time on shifting after driving occasionally with tow/haul on. Maybe placebo, but seems better even though I've never thought there was much of an issue.

 

I DO like the grade braking when towing...big help.

[Jeff5347]

Do all 15...sierras and silverados have grade braking. I do notice an active braking when slowing down but thought grade braking was a option not standard. Mine is a 15 Silverado Lt 5.3 w tow package 3.42 gears

 

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[scott.moody.9401]

i was coming down a fairly steep grade (I checked the offroad DIC and it said 5%) in my '16 and I got a pop up message that grade braking was active and noticed it holding speed. Surprised but annoyed me at the same time

 

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[Rkaroll953]

my grade braking never works when not in tow haul but i will give it a shot by turning it off and seeing if it gets a little smarter.

[scottl1346]

going to try this mine clunks bad and weird shifting all the time.

[O_J_Simpson]

Why can't GM just steal Ford's Sport Mode? Nothing like a factory performance tune at the push of a button.

[Deanjo]

So while certainly not as vocal... I do notice occasional odd behavior with the trans and shifting in my 2015 Sierra 1500 SLT.

 

I was chatting with a friend of mine I know through a local car club, and it turns out he's actually one of the senior techs at a GMC dealer a few towns over. So I've been trying to pay closer attention when the trans does something funny (harsh 2-3 upshift, delayed downshifts, occasional shudders, feels like it gets "stuck" in a lower gear then pops, etc.) and relaying it back to him.

 

He hit me up the other day and told me to disable grade braking, and let him know how the truck feels.

 

To disable grade braking, you hold the Tow/Haul button down for a few seconds, then release it. (This is NOT "hill descent control"). You get a popup on the DIC that says it's been disabled.

 

It definitely makes a difference. I was concerned it was just placebo effect... but he confirmed my observations are what they expect to see. Much smoother shifting. No more "confused" feeling by the trans. No more odd clunks.

 

He told me "they" think they're narrowing in on the problem. I assume he's talking about GM/factory. Says one of his co-workers (also a tech) is a big truck nerd and has been trying to sort this stuff out with his own truck.

 

Give it a shot. Let me know if you feel the same thing I do (for my own curiosity's sake).

 

 

 

 

I could buy you a few beers right now. Just tried it since reading and the shifting in the city is like a night a day difference. No bogging down on the 3rd to 4th shift, no dead spot, crisp shifts. Now if they would only make it so you didn't have to set it each time after starting the truck that would be great.

[OmniGLH]

I'm just glad to hear that I'm not the only one who noticed an improvement.

 

I'll talk to him tomorrow (dropping the truck off to him to look it over + oil change), I'll try to remember to confirm but I'm pretty sure he (or his co-worker) got the idea to try disabling the grade braking from GM. I do recall him telling me, "Yeah 'they' are narrowing in on the problem with these transmissions."

[Edelman13]

Do all 15...sierras and silverados have grade braking. I do notice an active braking when slowing down but thought grade braking was a option not standard. Mine is a 15 Silverado Lt 5.3 w tow package 3.42 gears

 

Sent from my Nexus 6P using Tapatalk

I have the same truck and have grade braking. Used to kick in often. Now it almost never does

[thearizonacowboy]

I've had my truck tuned by Diablew but every once and a while I have a wonky downshift. I just disabled the grade braking and after about 75 miles of driving, every shift was crisp.

I'll keep it disabled and drive it some more to see how she does.