2015 Gmc Sierra 1500 SLT ( Transmision issues )

[epelaez86]

Hi Guys,

I'm new to this site forum and I was wondering if I can get some answers before I get this tuner for my truck.

The issues that am having my truck are the fallowing:

1- the accelerations is horrible, it jerks around a lot when accelerating and decelerating.
2- when I'm cruising at a certain speed, lets say 40mph and I let go of the accelerator for a split second and I hit it again to change lanes, the tranny sometimes jerks really hard and sometimes it hits and it makes a loud clunk noise.
3- when downshifting, it fells like its doing it really hard and fast, it also hits and makes a loud clunk noise sometimes.

I keep reading online that this might be all fixed by putting a tuner on but I just wanted to verify if someone has had this issues before and if it has been fixed with a tuner. any info will be greatly appreciated. thank you

my truck is completely stock.

[06MonteSS]

what tranny, the 8-speed with 6.2? 8 speed tranny is not supported, can't do anything about it.. lot of people having issues with the 8 speed tranny, have seen on forums that GM actually has some programming updates out for it because they know there are issues..

if it's the 6 speed tranny and 5.3, sounds like you have tranny issues, shouldn't be doing that.. so I would recommend taking it to your dealer to check it out and again, there may be GM programming updates to fix things up. if it's banging/slamming into gear now, totally stock, something isn't right...

[epelaez86]

its a 5.3l with a 6 speed.

I have taken it to the dealer a couple of times and they keep telling its fine. they told me that the reason its making the clunking noise is because the gears are engaging. that's BS.

I read on other forums that a tuner can fix this issue by keeping more pressure on the tranny so it can shift better. I don't know what else to do at this point, its a brand new truck with 7k miles only.

[epelaez86]

its a 5.3l with a 6 speed.

I have taken it to the dealer a couple of times and they keep telling its fine. they told me that the reason its making the clunking noise is because the gears are engaging. that's BS.

I read on other forums that a tuner can fix this issue by keeping more pressure on the tranny so it can shift better. I don't know what else to do at this point, its a brand new truck with 7k miles only.

[HoosierZ]

Try turning off the Grade Braking and see if it makes a difference. Some guys have said that it helps with the clunky shifts. To disable the grade braking, hold in the tow/haul button for 5 seconds and release it. A message will pop up in the display to tell you it is disabled. You'll need to do it every time you start the truck. I've noticed my 2016 Silverado doesn't seem to have the surge it had in 2nd gear below 1500 rpms.

By the way, I'm running the stock tune. I'm waiting a while to put my tuner on.