Who likes their 6 Speed?

JacobC1983 · September 23, 2017

Nobody has this happen, huh? Maybe I need to take my truck in.

Limited360 · September 23, 2017

I have noticed something with this 6 speed (2016 CC, SLT, 5.3L)

When I am on the highway or in my neighborhood going down a hill and I let off the gas for about 10 seconds, I feel the torque converter lock or unlock, resulting in the truck surging forward and sometimes clunking.

Does anybody else feel this? The truck isn't shifting... it is just the feel of the torque converter lock or unlock (I don't know which)

I have had this feeling, its almost like the driveline is crossing a lash line somewhere and it is being amplified due a resoanance at these low speeds, it can feel 'violent' at times, sounds bad if its the same thing I have experienced. Mine is extremely rare.

nitro882 · September 27, 2017

The TPS has been checked and shown to be good, it has done this since the day i bought the truck so its not a new thing. Like i said this particular thing only happens when i get off the throttle suddenly at the exact same time as it is upshifting. Otherwise it does not hesitate for 3 seconds like this. I still have other gripes with the transmission like harsh shifts and sometimes it hunts for the right gear. I think its programmed poorly, my dealers transmission guy thinks the same and off the record he has suggested a tune to try to fix it since GM wont. I have not tried a tune yet but its in the near term plans.

Quick update, I ordered a Diablo Intune 3 and applied a tune to the truck. I used the standard diablo 93 octane tune, transmission firm programming and shut off afm. I left the upshift torque control alone. It’s like driving a different truck now, all and I mean all of the drivability issues are gone. No more clunky slow shifting transmission and no more afm stumble. The truck drives like it should wether I’m taking it easy around town, cruising on the freeway or mashing the gas. I did lose a couple things of mpg but it’s worth it, the 6.2 is thirsty anyway so a couple tenths is no biggie.

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yamaha0343 · October 4, 2017

So far, (only about 3k in, 300 miles towing) mine has been fine. Haven't noticed anything anyway.

Limited360 · October 4, 2017

One of my largest pet peves is how bad the trans wll shift when not towing after just completing a road trip while towing in tow haul... Slams on shifts... takes ~25 miles to work itself back to normal it would seem.

heavyhitter · October 5, 2017

I hate feeling the downshifts when I slow down or brake. Never had that issue in an automobile.

No Tyme · October 5, 2017

I hate feeling the downshifts when I slow down or brake. Never had that issue in an automobile.

Try disabling "Grade Braking" and I believe you will see a great difference.

heavyhitter · October 5, 2017

Try disabling "Grade Braking" and I believe you will see a great difference.

Thanks No Tyme!

Mine was on, the ride to work was bumper to bumper and raining so I cant tell yet but that might be the ticket.

Knotsure · October 5, 2017

15000 more miles and I am getting a tune. Hoping the tranny will smooth out then. My 6 speed is usually ok but sometimes it has its moments where it’s gets confused or shifts up to quickly.

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No Tyme · October 5, 2017

Thanks No Tyme!

Mine was on, the ride to work was bumper to bumper and raining so I cant tell yet but that might be the ticket.

Disabling Grade Braking improve a great deal the operation of my 6 speed. Unfortunately after opening 2 complaints with GM the complaints were closed with the answer of "The Transmission is operating as designed". Well, I guess it is a design flaw them because so many people think that it decreases the drivability of the truck a great deal.

But who am I: just a loyal customer who had to spend hundreds of dollars to improve the drivability of my 40K plus truck.

RideZX6R · October 9, 2017

Disabling Grade Braking improve a great deal the operation of my 6 speed. Unfortunately after opening 2 complaints with GM the complaints were closed with the answer of "The Transmission is operating as designed". Well, I guess it is a design flaw them because so many people think that it decreases the drivability of the truck a great deal.

But who am I: just a loyal customer who had to spend hundreds of dollars to improve the drivability of my 40K plus truck.

How do you disable it? tune only?

nluchau · October 9, 2017

How do you disable it? tune only?

Hold down tow/haul for 5 seconds will disable it during that engine on cycle.

No Tyme · October 9, 2017

Hold down tow/haul for 5 seconds will disable it during that engine on cycle.

It is that simple, but once you try it and like it, you will have to hold the button in evert time to start the engine to feel the results.

I just seems backwards to me, as most people don't have a trailer hooked up all the time. My belief is it should be disabled by default, but GM doesn't think this way..

RideZX6R · October 10, 2017

Hold down tow/haul for 5 seconds will disable it during that engine on cycle.

TY sir!

nluchau · October 12, 2017

On 10/9/2017 at 4:30 PM, No Tyme said:

It is that simple, but once you try it and like it, you will have to hold the button in evert time to start the engine to feel the results.

I just seems backwards to me, as most people don't have a trailer hooked up all the time. My belief is it should be disabled by default, but GM doesn't think this way..

When I tried this the first time I really never noticed a change but when I do it now I can feel the downshifts are a bit tamer but still really noticeable. What are you experiencing when turning off grade braking?