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

InertiaFaze · May 12, 2016

after about 2 weeks of driving without grade braking (disabling every time.......) I can say the clunk is gone, most of the downshift hesitation has been minimized. fuel economy does not seem to be any better, but it it still about the same. getting 12.6 to 12.7 L/100km (~22mpg) using both in the dash and calculation from pump.

Need a way to disable this outright, trying to find a guy with tech2 that can program this out or disable it by default.

Very good report. Question. Before your 2 weeks of driving without GB, did you regularly notice the "Grade Braking Active" message on the DIC? It only appears once per key cycle, but curious if you ever noticed it. Do you live in a hilly terrain environment? Are you a light braker (for long duration)?

morrislee · May 12, 2016

Very good report. Question. Before your 2 weeks of driving without GB, did you regularly notice the "Grade Braking Active" message on the DIC? It only appears once per key cycle, but curious if you ever noticed it. Do you live in a hilly terrain environment? Are you a light braker (for long duration)?

Not much hills where I live. I drive mostly highway and all downtown is a little bit of hill only.

Never seen the message and i am a light braker

fondupot · May 12, 2016

Not much hills where I live. I drive mostly highway and all downtown is a little bit of hill only.

Never seen the message and i am a light braker

Try turning it off though. You will notice a difference. Even on a slight grade. I've noticed the message doesn't always pop up when its engaging.

morrislee · May 12, 2016

Try turning it off though. You will notice a difference. Even on a slight grade. I've noticed the message doesn't always pop up when its engaging.

Read a few posts before i have my report

wulfgott · May 12, 2016

I really hope GM looks into this and maybe get a definitive answer via TSB or something. I have been turning it off pretty routinely and still notice the difference. Most noticeably when I forgot to turn it off yesterday. I go to merge with traffic just as I always do and do my routine drive and I honestly thought something was wrong with my truck as I have gotten used to driving over the last week with it turned off and had forgotten what it was like not to have smooth shifting and get up and go. I hit the gas and there was no get up and go at all and a reasonably rough up shift.

fondupot · May 12, 2016

Read a few posts before i have my report

Saw that after I posted.

BIGDOGx · May 12, 2016

Brought it in again for the service writer to look at it as he found a few bulletins regarding grade braking and a check list of making sure connections are tight and a relearn of the brake position sensor so GM is clearly aware there is a problem with it. Told him i would drive it for the week without disabling and not sure i'm going to make the week as it clearly didn't fix anything.

Gm is either going to fix this problem or appease me by crediting me the money i spent on the extended gmpp warranty along with free cash for accessory's of my choice!

kp52 · May 12, 2016

I really hope GM looks into this and maybe get a definitive answer via TSB or something. I have been turning it off pretty routinely and still notice the difference. Most noticeably when I forgot to turn it off yesterday. I go to merge with traffic just as I always do and do my routine drive and I honestly thought something was wrong with my truck as I have gotten used to driving over the last week with it turned off and had forgotten what it was like not to have smooth shifting and get up and go. I hit the gas and there was no get up and go at all and a reasonably rough up shift.

I just traded my '15 Silverado for a '16 5.3/6sp SLT and its amazing how much they shift the shame. You would think maybe they would have changed something.. Same deal, if I forget to turn off the grade braking I can tell pretty quick, luckily its easy enough to turn off.

There for sure is a difference on hills though on how muck braking you need, on severe hills when you ride the brakes the DIC will say 'grade braking active' but on smaller hills you can still feel it. If you turn it off you can feel the difference, so like someone posted above I'm sure GM left it on by default in case you were loaded. Which is cool and all but man it makes the trans shift like crap 80% of the time

Shu · May 12, 2016

so like someone posted above I'm sure GM left it on by default in case you were loaded.

Would have been nice to have it only activate when the tow/haul switch/mode was activated. I can see it's use when hauling heavy loads or towing but not in normal unloaded day to day driving.

kp52 · May 12, 2016

Would have been nice to have it only activate when the tow/haul switch/mode was activated. I can see it's use when hauling heavy loads or towing but not in normal unloaded day to day driving.

I agree, but like so many other nanny and CYA things on cars these days I doubt they will change it. For now at least we can turn it off..

wayles · May 14, 2016

Add me to the list of believers. I tried it for the first time tonight and saw a BIG improvement in drivability. Not perfect. Still the occasional wonky shift, but much, much better.

I have a '15 with the 6.2 and 8 speed

Silver ice 6.2 · May 14, 2016

I have made this a everyday thing every time I start the truck

f8l vnm · May 14, 2016

I still get some clunks but the shifts and confusion seem to be cleaned up a quite bit. I pretty much do it has a habit now. It reminds me of my mustangs , comaros and vettes I had , I used to turn off the traction control as soon as I turned on the car.