Grabby braking and downshifting when stopping

heavyhitter · October 5, 2017

When I brake, my brakes kind of feel grabby and fade grab and fade. I also notice that transmission downshifts when I slow down and stop and this exacerbates the problem. The tach will jump up and you will feel it braking for you (the way a down shift feels dropping in a lower gear)

I guess what I'm saying is when I slow down its not a smooth linear deceleration and you need to press down pretty good to slow down. Is this characteristic of the truck? The only grip I have with my truck so far is the horrible feel at the brake and gas pedal. The gas pedal was fixed with a shim and hit solved the issue wonderfully.

rgoldberg · October 5, 2017

I have the same complaint about the hard downshifting while braking. I plan on contacting my service advisor tomorrow and seeing if they have a transmission update to address this.

heavyhitter · October 5, 2017

I have the same complaint about the hard downshifting while braking. I plan on contacting my service advisor tomorrow and seeing if they have a transmission update to address this.

Someone told me to turn off hill decent braking.... Mine was on, the ride to work was bumper to bumper and raining so I cant tell yet but that might be the ticket.

Hold in your trailering button for 3 seconds it will turn off.

rgoldberg · October 5, 2017

Someone told me to turn off hill decent braking.... Mine was on, the ride to work was bumper to bumper and raining so I cant tell yet but that might be the ticket.

Hold in your trailering button for 3 seconds it will turn off.

I noticed this coming on often when towing a trailer from SC to FL. Never understood why. I will deactivate the hill decent tonight! Thanks!

dubwise · October 6, 2017

FYI-

A tune from blackbear performance will fix the upshift/downshift garbage software transmission programming from the factory.

No dealer will be able to address this.

nluchau · October 6, 2017

Is yours a 6 speed?

My 2016 with a 5.3 6 speed has had the firm bump downshifts since I bought it with 12 miles. Right now I have 14k miles. Same downshift bump no matter what I do. I've tried all the tricks by disabling grade braking, etc... I find it still tough to get used to but anyone I talk to says its normal. I shimmed my gas pedal too because it was sloppy, made a big difference for that anyway.

I tend to agree with dubwise, to eliminate the downshift garbage it will need to be tuned. I won't do this since I want to keep my warranty.

GM are you listening to us?!?!?!?!

Dmf10e · October 6, 2017

Is yours a 6 speed?

My 2016 with a 5.3 6 speed has had the firm bump downshifts since I bought it with 12 miles. Right now I have 14k miles. Same downshift bump no matter what I do. I've tried all the tricks by disabling grade braking, etc... I find it still tough to get used to but anyone I talk to says its normal. I shimmed my gas pedal too because it was sloppy, made a big difference for that anyway.

I tend to agree with dubwise, to eliminate the downshift garbage it will need to be tuned. I won't do this since I want to keep my warranty.

GM are you listening to us?!?!?!?!

I agree. Supposedly it's normal, including the words from the dealer. I have a 4.3 6 speed, but will wait until the warranty ends before I tune. As far as the shim, can you post a pic of where to put the shim? Tried to look the other day, but couldn't figure out where to place it.

nluchau · October 6, 2017

See this video, shows you where to put it. Exactly how I have mine.

Western96 · October 7, 2017

Got the same thing with mine, it's just the way GM programmed it from the factory. I really don't mind it that much, anything that helps me slow down faster is a plus in my books. That "grab and fade" you're feeling is probably the engine RPM's going up and down as the transmission shifts into a lower gear, like how it would with downshifting a manual transmission.

Definitely took some getting used to but this thing stops soooo much faster than my old 04 Ram, it's not even close.

rgoldberg · October 8, 2017

I have a 2016 5.3 6 speed, disabling Grade Braking made a huge difference this weekend while towing a 16' dual axel trailer carrying wood, metgal sheeting, a 4 wheeler, and a bush hog. With grade braking on it would downshift and rpm would jump to 4k, with grade braking off it would down shift normally to about 2-2.5k.

From now on disabling Grade Braking will be part of my start up procedure.

sk · October 12, 2017

On 10/5/2017 at 9:15 AM, heavyhitter said:

Someone told me to turn off hill decent braking.... Mine was on, the ride to work was bumper to bumper and raining so I cant tell yet but that might be the ticket.

Hold in your trailering button for 3 seconds it will turn off.

Just FYI -- that is correct but you are turning off "Grade Braking".

Hill Descent Control is a completely different system that only comes on the Z71 and All-Terrain trucks.

JimCost2014 · October 12, 2017

Hill Descent is a "crawl" feature, you have to turn it on/off and is used in moderate/extreme downhill use, off-road, bad weather, etc.... Only comes on certain models, Z71's, Denali's, upper trim levels. If you do not have the switch in the center stack, you do not have the feature.

Lost Hog · October 14, 2017

I just had my '17 in for the same thing. Felt like it was prematurely downshifting. The service report states that they ( reprogrammed ECM module SPS update software) it shifts smoother now. Not perfect but I can say its much better. Hope this helps.