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Letter from GMC today re rough trans & hesitation on 6.2L engines

Linecapt
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Linecapt Enthusiast

Linecapt

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I got a letter in the mail today from GMC regarding my 2016 Sierra with the 6.2L engine that "may have a condition that affects the electrical connection to the transmission oil temperature sensor.  If this condition occurs, rough transmission shifts or hesitation during acceleration may occur.  Additionally, the Malfunction Indicator Light (Check Engine Light) would illuminate and a diagnostic trouble code related to the temperature sensor would set."  They're extending protection to 10 years or 120000 miles.  

 

Has anyone else with the 6.2L engine received this letter?  Does anyone think this relates to what everyone always complained about, the rough shifts and the hesitations that we've long complained of?  

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mookdoc6 Senior Enthusiast

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On 9/2/2020 at 6:09 PM, Linecapt said:

I got a letter in the mail today from GMC regarding my 2016 Sierra with the 6.2L engine that "may have a condition that affects the electrical connection to the transmission oil temperature sensor.  If this condition occurs, rough transmission shifts or hesitation during acceleration may occur.  Additionally, the Malfunction Indicator Light (Check Engine Light) would illuminate and a diagnostic trouble code related to the temperature sensor would set."  They're extending protection to 10 years or 120000 miles.  

 

Has anyone else with the 6.2L engine received this letter?  Does anyone think this relates to what everyone always complained about, the rough shifts and the hesitations that we've long complained of?  

I have surmised that from the beginning the junk wiring harnesses on 2015-2016 on 5.3/6.2 8L90 Transmissions along with the super fancy 6 pin MAF sensors that are so sensitive to Dry,Humid air and their corresponding densities and temperatures.....Got a Crap 8L90?  Drive it in the rain and report back....Yeah, it's coupled with Hygroscopic oil which amplified the drive-ability issues.   GM can't figure out what day the trans drives better astonishing.....but hey?  nobody listens to me....................

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Grumpy Bear Senior Enthusiast

Grumpy Bear

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5 minutes ago, mookdoc6 said:

I have surmised that from the beginning the junk wiring harnesses on 2015-2016 on 5.3/6.2 8L90 Transmissions along with the super fancy 6 pin MAF sensors that are so sensitive to Dry,Humid air and their corresponding densities and temperatures.....Got a Crap 8L90?  Drive it in the rain and report back....Yeah, it's coupled with Hygroscopic oil which amplified the drive-ability issues.   GM can't figure out what day the trans drives better astonishing.....but hey?  nobody listens to me....................

You sound like my dad. His favorite is, "But hey don't listen to me, I'm just a dummy". You two should meet. :) 

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martha3065 Enthusiast

martha3065

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 Does anyone think this relates to what everyone always complained about, the rough shifts and the hesitations that we've long complained of?  


I doubt it is the cause of all the complaints. Mine has had those symptoms since nearly new, as does a buddy's. Probably gets worse under this condition. I do think this is the same issue members have posted on here: https://www.gm-trucks.com/forums/index.php?/topic/224729-Money-Light-on-8-Speed,-P0700+P0711
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Ltz4 me? Enthusiast

Ltz4 me?

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Mine was just fixed b/c of this code on a 16' Silverado 5.3l 8speed m5u tranny.

While the pan was dropped I had them completely drain all bad fluid completely, new tranny filter, new best blue label Mobil 1, new 2 piece wiring harness, transmission relearn.

We will see...it did start shifting really.bad when check engine light came on,( po711)

Transmission temperature sensor was verify ok by the ohm reading taken.

If I can I'm flipping my pill to reduce the oil temperature ( I'm regularly seeing 185-195deg.f)

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Z45 Senior Enthusiast

Z45

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185-195ºF is NORMAL operating temp for an automatic transmission.  It runs at peak efficiency at those temps as its DESIGNED to do.  I don't understand why people fell this is bad, its not. Its paranoia.     

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mookdoc6 Senior Enthusiast

mookdoc6

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On 9/4/2020 at 8:10 PM, Grumpy Bear said:

You sound like my dad. His favorite is, "But hey don't listen to me, I'm just a dummy". You two should meet. :) 

Your pops is probably pretty neat guy and holding up well at his age.  Most of my knowledge base is from people of that generation...I reckon there is not much of substance I have learned from the younger folks.  they can put an "APP" on my phone but that's about all...............

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CadillacLuke24 Enthusiast

CadillacLuke24

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On 9/5/2020 at 7:05 PM, Ltz4 me? said:

Mine was just fixed b/c of this code on a 16' Silverado 5.3l 8speed m5u tranny.

While the pan was dropped I had them completely drain all bad fluid completely, new tranny filter, new best blue label Mobil 1, new 2 piece wiring harness, transmission relearn.

We will see...it did start shifting really.bad when check engine light came on,( po711)

Transmission temperature sensor was verify ok by the ohm reading taken.

If I can I'm flipping my pill to reduce the oil temperature ( I'm regularly seeing 185-195deg.f)

Do you have a part number for the new 2-piece wiring harness?

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STurner15 Enthusiast

STurner15

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Got my letter in the mail and took it in immediately. 74k miles 6.2L. They flush the trans with new fluid and replace seals etc etc. have about 20-30miles on the truck now and it seems to run better. But I got a flush around 65k and it worked for a little while... so I am hoping this harness and flush works.... for a .. little while.... longer...

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flyingfool Senior Enthusiast

flyingfool

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On 9/6/2020 at 3:23 AM, elcamino said:

185-195ºF is NORMAL operating temp for an automatic transmission.  It runs at peak efficiency at those temps as its DESIGNED to do.  I don't understand why people fell this is bad, its not. Its paranoia.     

sure, back when a transmission was all mechanical, they could take the heat...  but now they put delicate plastics, seals,  platic check balls and a tcu in the hot boiling transpan.. yeah that will make it reliable, sure!

 

 

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lucas287 Enthusiast

lucas287

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On 10/30/2020 at 9:24 AM, STurner15 said:

so far so good on my end. added a couple pounds to low end gears shift pressures. smooth and solid still.

Did you do this in HPtuners? If so what table(s) did you change? I'm always tinkering here and there with my tune. 

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