My own 8 speed problems & resolution

diyer2 · January 30, 2018

In this world of smart phones, computers, tablets and the internet, I thinks it's unbelievable the masses are not informed.

huntr1117 · January 30, 2018

It's sad to say that this is the main reason I'm looking forward to my warranty expiring. As soon as it ends I'm sending my TCM to HP Tuners to get unlocked so I can have the engine and trans properly tuned. Other than the 8 speed joke of a transmission I love the truck.

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MY164X4 · January 30, 2018

It's sad to say that this is the main reason I'm looking forward to my warranty expiring. As soon as it ends I'm sending my TCM to HP Tuners to get unlocked so I can have the engine and trans properly tuned. Other than the 8 speed joke of a transmission I love the truck.

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What's the average cost of that TCM to HP tuner piece?

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huntr1117 · January 30, 2018

What's the average cost of that TCM to HP tuner piece?

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I'm pretty sure just to get it unlocked it's $200.

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benelli · January 30, 2018

4 hours ago, JUS1MO said:

Benelli, I believe you are correct in your assessment of our situation. We don't have a leg to stand on in this. I will never understand how they keep selling these trucks at a rapid rate to unsuspecting people. I guess the word doesn't get out to the buying public. I certainly never heard a word about it before I bought one.

Because the incentives are good with 0%84 months sometimes we get all excited about buying a new vehicle we really don’t research them. I will never buy another Gm even if they would replace my truck for free. Just because of there customer service IT SUCKS They lie and hide behind the true facts why these vehicles have this problem. The general public is not stupid as they would like us to be . It’s all about sales and filling dealer pockets.

JUS1MO · January 30, 2018

59 minutes ago, benelli said:

Because the incentives are good with 0%84 months sometimes we get all excited about buying a new vehicle we really don’t research them. I will never buy another Gm even if they would replace my truck for free. Just because of there customer service IT SUCKS They lie and hide behind the true facts why these vehicles have this problem. The general public is not stupid as they would like us to be . It’s all about sales and filling dealer pockets.

Right again Sir. I personally can't just get another truck. Actually if I could, I don't know what I would get with all the other brands having troubles of their own. The biggest problem in the vehicle industry today is "Big Government" interference into such things as emissions, fuel mileage, EPA, global warming and all the other things they want to control. Back in the good ole' days we could build a motor, transmission, and rear end to do what we wanted without a computer and it would work perfectly until we blew it up. If you had a diesel all you needed was fuel and clean air to make all the power you wanted. Those days are long gone never to be seen again.

benelli · February 1, 2018

On 1/30/2018 at 2:19 PM, JUS1MO said:

Right again Sir. I personally can't just get another truck. Actually if I could, I don't know what I would get with all the other brands having troubles of their own. The biggest problem in the vehicle industry today is "Big Government" interference into such things as emissions, fuel mileage, EPA, global warming and all the other things they want to control. Back in the good ole' days we could build a motor, transmission, and rear end to do what we wanted without a computer and it would work perfectly until we blew it up. If you had a diesel all you needed was fuel and clean air to make all the power you wanted. Those days are long gone never to be seen again.

Your 100% right about that. Sad as a brand that GM or any manufacturer has lost all pride in building quality vehicles anymore. they all look great but hide behind plastic and cheapest parts that the car manufactures can buy. My Brotherinlaw works at Chrysler and told me if you see the crap that goes into there builds you would put your hands on your head. I think i may just lease from now on and not worry about rustproofing and all the high end oils and parts to keep the truck for a long time. I think those days are gone hanging on to your truck forever no matter how well you take care of it.

benelli · February 1, 2018

On 8/1/2017 at 3:17 PM, MOhunter92 said:

Had a tcm update done to my transmission 2016 sierra all terrain slt, 5.3 8 speed (it was absolutely horrible and I dreaded driving it, terrible 3-1 down shift and sloppy shifting overall, very severe clunks and shudders) and literally feels like a different truck. It is smooth as silk, I am absolutely thrilled. It was a one year battle for me to try and get this truck to shift right. I'm so excited, still in shock! I will be sure to post the service receipt once I get it.

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Were`s the service reciept to see what they did?

rickdi321 · February 8, 2018

I own a 2017 denali which does the same thing, I have had it to the dealer for repair of the hard shifting at low speeds and when down shifting they did a relearn and two updates and it still clunks and does the same thing I guess thier is no fix, I'm very disappointed as ever thing else with this truck is good I just don't understand why gm . Would not fix this issue as this hurts this brand in a very competitive market for trucks it's like they hope that looks and features are enough and it's not true drive ability is even more important I would be afraid to buy the new ten speed 2019 model if they can't get this one right

benelli · February 10, 2018

On 11/7/2017 at 9:54 PM, B R A D said:

Part 3. I dropped the truck off yesterday and picked it up this afternoon. The Chevy/Cadillac dealer have so far been extremely pleasant and courteous, no complaints there. I was told the internal parts were coated with something to prevent rust and was getting mixed with the transmission fluid and not doing well together. They flushed the system with 20 quarts and filled back with 8. Said I was supposed to drive for around 600-800 miles and that it may still do it a little during this period and that if continued to do it afterwards to let them know and they would proceed further. I also didn't buy the truck at this dealer but at another of the same name just different location and they have been nice enough to give me a loaner 2x already. I can definitely see wanting to do future business with this dealer, the service department can really make a difference.

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They used the wrong transmission fluid in the 2015 and 16 i was told by the Transmission tech at the dealer i bought from. All this tech does is software and tear downs of these transmissions. I mentioned in a earlier post that i went on a test drive with him and he told me its basically a software issue with the transmissions for this harsh shifting. He said think about it if aftermarket tuners clean up the shifts and people are reporting good results in the 2017 why would the transmission need flushing because oil different oils mixing. Bull Crap. No doubt that we probably have the same transmissions as the 2015 16s in our 2017 trucks. the flushing 3 times and refillling was because they used the wrong fluid in the transmissions back in 2015 2016. so the fix was to flush 3 times and fill with Mobile 1 Hp trans fluid to correct the problem. spoke to my dealer this week and expressed my disappointment with this truck and the way that GM rights this off as normal operation. He said well maybe you can trade it in for a new one they have the 10 speed in there now. LOL . Ya right they cant get the last 3 years of transmissions right what makes you think this would be any better. The blow smoke up peoples A***s and expect everyone to just believe them. Ill Say it again i believe the grunt mechanic that comes in in the morning and puts a full day of work in over these clowns at the dealerships that are only there to sell there $60.000 junks to honest working people.

Rme2513 · February 15, 2018

Has anyone had a vibration or shutter on heavy acceleration from a stop mine will do it then and under heavy load at low rpm I have already had one converter replaced for shutting during a steady speed

Bigmac · February 16, 2018

5 hours ago, Rme2513 said:

Has anyone had a vibration or shutter on heavy acceleration from a stop mine will do it then and under heavy load at low rpm I have already had one converter replaced for shutting during a steady speed

Yes I am still working this exact problem. 2017 GMC 6.2 Max Tow. 2 converters and a complete trans and it is still present. Not to bad but still present till I load it pulling my trailer then it really shakes. Appears when it shifts 1-2 and continues on thru 4 at 1200-1800 RPM. When I get back home ( In Arizona for several months) I am to meet with District Engineer to see if it can helped. It feels like a vibration in driveline. Love the truck except for this problem.

HondaHawkGT · February 22, 2018

On 2/15/2018 at 6:36 PM, Bigmac said:

Yes I am still working this exact problem. 2017 GMC 6.2 Max Tow. 2 converters and a complete trans and it is still present. Not to bad but still present till I load it pulling my trailer then it really shakes. Appears when it shifts 1-2 and continues on thru 4 at 1200-1800 RPM. When I get back home ( In Arizona for several months) I am to meet with District Engineer to see if it can helped. It feels like a vibration in driveline. Love the truck except for this problem.

Are you in tow/haul mode when pulling this trailer?

Bigmac · February 22, 2018

4 hours ago, HondaHawkGT said:

Are you in tow/haul mode when pulling this trailer?

Yes but will do it with 300 lbs of weight in back. It can be felt running empty but not as severe .

HondaHawkGT · February 22, 2018

7 hours ago, Bigmac said:

Yes but will do it with 300 lbs of weight in back. It can be felt running empty but not as severe .

Corvette and Camaro guys with the 8L90 have reported the shudder being fixed after the dealer replaced the converter and performed a couple trans+trans cooler flushes, with the filter being changed along with it. The friction material in the TC clutch appears to get into the system and cause the shudder. It's a very common issue with F-150 transmissions the last few years too.