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

Rkaroll953 · May 3, 2016

only place i have noticed a difference is coasting to getting back on the throttle there is no wierd transition it just goes. other than that no change.

aggieguy03 · May 3, 2016

2014 DC 4x4 5.3 6 sp 3:42 with leveling kit and stock 18" wheels/tires. Definitely improved the up and down shifts timing as well as coast to brake and brake feel.

dnb2014 · May 3, 2016

Coasting is better doing this and I was able to gain 1MPG. There is different performance characteristics from pushing the button while parked versus doing it while driving or in gear. But my mileage has improved from this only when babying it is when It comes in handy otherwise no difference. Have not tried it on E85 yet.

aggieguy03 · May 3, 2016

2014 Z71 CCSB with 3.42s, a 2.5" leveling kit and 285/65/20 KO2s on it, and felt a big difference. I hit a lot of traffic on the way in today, so I couldn't open it up and pass a lot like I normally do. In city driving, it was a noticeable change. It struggled in the neighborhood leaving, especially between 2nd and 3rd, but that normalized as I got out of there. Thank you for sharing this tip!

HiggySTL · May 3, 2016

I tried it out for a couple days and can tell a difference as well. My gas mileage hasn't increased, but I can tell it will just coast now when I let off the gas and it doesn't feel like it is being throttled back like before. I really like that.

Also, it seems like city driving is better, the shifting response seems to be improved. For example: if I am slowing down for a red light, then the light turns green and I press the accelerator; previously it would studder a little sometimes and act as though it is in too high of a gear. It would have about a second or two of "gear confusion" and then it would finally downshift and go when I would give it a little more gas. Now it doesn't seem to always go to the higher gear and when I press, it seems to go a little smoother without the shifting confusion and hesitation.

I hope this is a sign that GM is finally on to something and will be willing to release an update for our trucks to address the shifting. Thanks OP for sharing the tip!

OmniGLH · May 3, 2016

I tried it out for a couple days and can tell a difference as well. My gas mileage hasn't increased, but I can tell it will just coast now when I let off the gas and it doesn't feel like it is being throttled back like before. I really like that.

Also, it seems like city driving is better, the shifting response seems to be improved. For example: if I am slowing down for a red light, then the light turns green and I press the accelerator; previously it would studder a little sometimes and act as though it is in too high of a gear. It would have about a second or two of "gear confusion" and then it would finally downshift and go when I would give it a little more gas. Now it doesn't seem to always go to the higher gear and when I press, it seems to go a little smoother without the shifting confusion and hesitation.

I hope this is a sign that GM is finally on to something and will be willing to release an update for our trucks to address the shifting. Thanks OP for sharing the tip!

Yep I always noticed the same thing. Slow down, then go to speed back up and the trans was all, "Hey wait I thought we were slowing down?" then after some hesitation I'd get a MASSIVE downshift and screaming engine.

Have not noticed ANY of that since I've started switching grade braking off.

SNOWMAN CUSTOM BAITS · May 3, 2016

2015 CCSB 4WD Z71 5.3 6spd 3.42. 2.5 leveling kit 285/70/17 mud tires 17x9 rims. 2100 miles

'01LS1 · May 3, 2016

only place i have noticed a difference is coasting to getting back on the throttle there is no wierd transition it just goes. other than that no change.

Have a 2013, so the old 900 series. Works the same & only noticed the same thing. A friend has a 2014 Yukon(old body style) & she noticed the same.

But personally have no odd shifts with my truck.

awd_rs · May 3, 2016

I question whether gear ratio has anything to do with this . I noticed a lot of guys with the 3.42 saying it was amazing . I have 3.08 and noticed nothing . ??

wulfgott · May 4, 2016

Don't hold your breathe, those "GM customer care" people are about as helpful as the secretary at the dealership.

While I am sure other people have had different and varying experiences with them than I as you seem to have had. I for one have had more than one good interaction with the GM Customer Care people on the forum. They were helpful and it directly led to a couple issues getting resolved in a timely manner.

On the topic though, I have been away from the forums for a few days and just came across this post. I will absolutely be trying this on my way home. I never really had any issues with my truck in regards to the shift wonkiness I have read about... that is until about 2-3 weeks ago. Right after I had the first oil change. I don't know if I just didn't notice the issues before or they just started at that point. It was right at 5k miles. The truck just seemed sluggish and shifting was odd with clunkink (nothing super major) and delayed bumping/jerking when coasting at 30-40 then hitting the gas again. or the very sluggish starts from red lights.

ToesonTheNose · May 4, 2016

you my friend get one adult beverage from me. I tried this this morning on my 2014 all star edition. First thing I noticed right away that 1st to 2nd gear confusion clunk was gone, especially in the stop and go city traffic, where it would hang on the gear to long then slam into next gear. it was so smooth and seemless, like it should be. I didn't get a chance to get on it yet, but I was amazed

Trucko20 · May 4, 2016

I sort of posed this question earlier in the thread, but didn't get much of a response. I just wanted to reiterate to see what anyone else thinks.....

Doesn't it seem kind of odd that GM wasn't able to come up with this idea already? I haven't tried it myself yet, but it sounds like almost everyone is reporting better performance AND increased MPG.....that's like the holy grail for truck makers.

Shouldn't it be a no-brainer that they would make this the default setting? That is.....unless they know something we don't know, yet. Is there a downside? Are we causing wear and tear on our trucks in some other capacity that hasn't made itself apparent yet?

I don't mean to be Debbie Downer, and I'm certainly not a mechanic, nor do I have any real in-depth knowledge about how this stuff works. It just makes my Spidey-sense tingle a little bit.....as the old adage goes, "if something seems too good to be true, it probably is."

I just wanted to kick this idea around.....I'd certainly love to hear others' opinions.

Dunc · May 4, 2016

I don't mean to be Debbie Downer, and I'm certainly not a mechanic, nor do I have any real in-depth knowledge about how this stuff works. It just makes my Spidey-sense tingle a little bit.....as the old adage goes, "if something seems too good to be true, it probably is."

I understand what you're saying, but I'd say that a car shifting like it should is not something that is too good to be true. I expect nothing less than proper shifting.

fondupot · May 4, 2016

UPDATE FROM BLACKBEAR PERFORMANCE:

Ladies and dudes, unfortunately, the Grade Brake Assist feature is controlled by the BCM, and NOT the TCM.

Strange....but I guess we need to figure out who can tune the BCM to disable this by default.

Anyone have ideas?

Newell33 · May 4, 2016

UPDATE FROM BLACKBEAR PERFORMANCE:

Ladies and dudes, unfortunately, the Grade Brake Assist feature is controlled by the BCM, and NOT the TCM.

Strange....but I guess we need to figure out who can tune the BCM to disable this by default.

Anyone have ideas?

I figured this was the case. This is why my junker still seemed to have issues, even after a custom tune.