issue Transmissions Issues/Problems

[Ron.s]

I've started having some pretty sever clunking going on when on/off the gas around 30-40kph (18-25mph). Its intermittent though so I'm not sure what the dealer can do about it. It will be fine for a week, then it might do this clunk and either get a surge of power or it feels like it just revs up without engaging. The clunk is getting loud enough that makes me look back to see if parts are laying on the ground.

 

This seems to be different than the 1-2 shift clunk I get when the truck is cold first thing in the morning. My truck has 42,000km (26,000mi) on it.

 

My bet is that your driveline Slip Yoke is sticking! My 14 did it and now my 16 too. I take to driveline shop and get it greased. Couldn't find a dealer to cover under warranty. Working as designed, ha ha!

[GMCustomerService]

Hello YJGUY,

We regret to hear that you are experiencing this intermittent concern in your Sierra. We understand how important the drivability of your truck is, and recognize how this can be frustrating. We would be more than happy to get you in touch with the proper teams that can best assist you in your region. Please send us a private message with your VIN, full contact information and preferred dealership.

 

All the best,

Julianne M.

GM Customer Care

I've started having some pretty sever clunking going on when on/off the gas around 30-40kph (18-25mph). Its intermittent though so I'm not sure what the dealer can do about it. It will be fine for a week, then it might do this clunk and either get a surge of power or it feels like it just revs up without engaging. The clunk is getting loud enough that makes me look back to see if parts are laying on the ground.

 

This seems to be different than the 1-2 shift clunk I get when the truck is cold first thing in the morning. My truck has 42,000km (26,000mi) on it.

[Tkeaton52]

Traveling home in my new (less than 1400 miles) 2500HD silvardo 6 hours from home the transmission started shifting very rough and then was missing gears. I pulled into a Chevy dealership and the service manager test drove the truck stating he was lucky to get back to the dealership. He stated that we probably needed a whole new transmission but now the regional manager says use parts to repair. The service manager and dealership were nice enough to provide us with a rental to get home.

[cNate]

Traveling home in my new (less than 1400 miles) 2500HD silvardo 6 hours from home the transmission started shifting very rough and then was missing gears. I pulled into a Chevy dealership and the service manager test drove the truck stating he was lucky to get back to the dealership. He stated that we probably needed a whole new transmission but now the regional manager says use parts to repair. The service manager and dealership were nice enough to provide us with a rental to get home.

Push back on that. You want a whole new one. If they saw no, then take your truck back and drive it until it breaks. Did that on a 2009 Chevy Suburban LTZ at less than 5k miles. They wouldn't even offer repair when it was slipping. Had to completely blow it out.

 

 

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[black00ta]

My 6speeds shifting behavior has gotten pretty bad now. (32k miles)

I quit mentioning it at the dealer as it became a waste of time. At this point I'm just waiting for something to break. I can even duplicate the problems and the dealer is clueless.

[No Tyme]

My 6speeds shifting behavior has gotten pretty bad now. (32k miles)

I quit mentioning it at the dealer as it became a waste of time. At this point I'm just waiting for something to break. I can even duplicate the problems and the dealer is clueless.

What is it doing?

[BlueTopaz14]

My brother purchased a 2017 Camaro two months ago, and at about 1100 miles he asked me to drive it because it was shifting weird, and it was, it's as if it didn't wanna shift, even if you were going 70 down the highway the rpms would suddenly shoot up and you'd start slowing down. We took it to the dealer and they said that because it's an 8 speed it was "hunting for a gear" so I insisted they keep checking on it and sure enough the computer module to the whole car needed to be replaced at just 1100 miles. Zero problems since!

 

 

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[Sierra Boy]

Nate805, on 21 Nov 2016 - 10:56 AM, said:Nate805, on 21 Nov 2016 - 10:56 AM, said:

Push back on that. You want a whole new one. If they saw no, then take your truck back and drive it until it breaks. Did that on a 2009 Chevy Suburban LTZ at less than 5k miles. They wouldn't even offer repair when it was slipping. Had to completely blow it out.

 

 

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My trans went at 2,581 and I asked to have it rebuilt instead of a new one as you don't know what you will get with a new one. At least I get to keep my original trans case but all the guts are new parts. They cleaned everything out and is brand new inside and has been perfect. I say, let them rebuild it from scratch it will be better in the long run if you plan to keep the truck.

 

GMC Sierra 2500 HD SLT

 

Sierra Boy

[emeryz28]

Does anyone else hear a friction/rubbing sound from the transmission during 1-2 and 2-3 shifts?

[black00ta]

What is it doing?

 

If i'm coasting around 30-40mph with my foot on the gas but not increasing speed it will clunk pretty damn hard as it downshifts for no reason, I can duplicate this easily. If I take off from a stop making a left or right hand turn it will short shift the 1-2 and bog itself down so low that it bucks and jerks and wont move, I can even floor it at it wont respond at all. It also gets stuck in the higher gears during cruising and will not accelerate on demand as it should. All of these symptoms have gotten worse as time has gone on.

[No Tyme]

 

If i'm coasting around 30-40mph with my foot on the gas but not increasing speed it will clunk pretty damn hard as it downshifts for no reason, I can duplicate this easily. If I take off from a stop making a left or right hand turn it will short shift the 1-2 and bog itself down so low that it bucks and jerks and wont move, I can even floor it at it wont respond at all. It also gets stuck in the higher gears during cruising and will not accelerate on demand as it should. All of these symptoms have gotten worse as time has gone on.

The transmission clunking may be the grade braking which is turned on automatically in your truck. Try this and see if it helps with that issue...

Disabling the grade braking by pushing in the tow/haul button for several seconds until you get a message in the DIC that "Grade Braking disabled". Then try to reproduce at the 30-40 mph speed.

This grade braking uses the transmission (I believe) to slow down the truck and that may be what your hearing.

 

This feature can be turned back on the same way, by simply holding the button in for several seconds as you will receive a message that is is engaged. It is also on by default every time you start the truck.

 

As for the engines performance while turning left I am not sure. Is you truck a 4 wheel drive? You do have the selector in 2 Wheel high correct?

 

I have experienced a couple of times my engine "flopping" as I call it, kinda like falling on it's face. Not a good feeling when you are trying to pull out into a round-about by a truck stop... I blame it on todays electronics.

[nadrojcote]

The transmission clunking may be the grade braking which is turned on automatically in your truck. Try this and see if it helps with that issue...

Disabling the grade braking by pushing in the tow/haul button for several seconds until you get a message in the DIC that "Grade Braking disabled". Then try to reproduce at the 30-40 mph speed.

This grade braking uses the transmission (I believe) to slow down the truck and that may be what your hearing.

 

This feature can be turned back on the same way, by simply holding the button in for several seconds as you will receive a message that is is engaged. It is also on by default every time you start the truck.

 

As for the engines performance while turning left I am not sure. Is you truck a 4 wheel drive? You do have the selector in 2 Wheel high correct?

 

I have experienced a couple of times my engine "flopping" as I call it, kinda like falling on it's face. Not a good feeling when you are trying to pull out into a round-about by a truck stop... I blame it on todays electronics.

I fixed my issue about just over a year ago, maybe this will help for others though.

[Jasadl]

Hi All!

 

My apologies if this information has been relayed previously. I didn't read all the post because ... well, I'm lazy. I too have been having the clunking problem, the V4 shakes, and the truck not being able to find a gear. Most of the driving I do in this truck is in moderate to severe traffic on 45 mph roads with a lot of stoplights (i.e. a lot of stop-and-go, quick speed-ups and slow-downs). Unfortunately, the truck just can't seem to balance the constant speed variations, the right gear, and V4 mode to make a comfortable ride. I have also been to the dealership and been told the same BS about adaptive learning, normal behavior, no codes, etc. etc.. Anyway, I have found the following has helped when "city driving:"

 

1. Turn off grade breaking (hold tow/haul button for 2-3 seconds, confirmation shows up on DIC)

2. Put truck in manual mode and select one gear less than what your transmission has (seems to disable V4 mode). I have the 6-speed so I use M5

 

I've been doing this for about a week now. Drastically reduced the number and severity of the clunks. My average MPG also went UP by .3 (I think this is because I can coast longer with grade breaking disabled). I do go back to regular drive when I'm taking long trips on the interstate.

 

Yes, I know it's unacceptable to have to do this EVERY time you start the truck considering what we paid for these things. I'm still working my case with GM for a permanent fix, but thought some of us could use a little reprieve while things are being worked out.

[black00ta]

The transmission clunking may be the grade braking which is turned on automatically in your truck. Try this and see if it helps with that issue...

Disabling the grade braking by pushing in the tow/haul button for several seconds until you get a message in the DIC that "Grade Braking disabled". Then try to reproduce at the 30-40 mph speed.

This grade braking uses the transmission (I believe) to slow down the truck and that may be what your hearing.

 

This feature can be turned back on the same way, by simply holding the button in for several seconds as you will receive a message that is is engaged. It is also on by default every time you start the truck.

 

As for the engines performance while turning left I am not sure. Is you truck a 4 wheel drive? You do have the selector in 2 Wheel high correct?

 

I have experienced a couple of times my engine "flopping" as I call it, kinda like falling on it's face. Not a good feeling when you are trying to pull out into a round-about by a truck stop... I blame it on todays electronics.

 

The grade braking has no affect on this condition =(

 

And the loss of power on turns is the same in 4x4 or 4x2 =(

[gambler1]

Anymore updates on this issue? mine is at dealership for this and a torque convertor.