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2015 GMC Acadia Denali
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Discussion Starter · #1 · (Edited)
Gooooood morning, Acadians!!!!
2016 Denali, AWD, 97k mi, NO codes.
I scoured the forum and all seems to apply to pre-2013 models.
Symptoms: delayed shift began during 3-4 shift, now has progressed to 2-3 shift. Engine temp climbs above median mark when car is in D and stopped. Radiator replaced at stealership Jan 2019, torque converter replaced right before super bowl 2020.
I have subscription to DIYAlldata, just need some guidance on what to tackle.
Love this forum and how descriptive you all are!! Looking forward to the replies!
 

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Are you using a scanner that can read all codes, including proprietary codes?

From your description, it sounds like a failing transmission control module.....but probably should visit a trusted transmission shop for proper diagnosis.
 

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Discussion Starter · #3 ·
I am using an Autel 619 scanner that can pull the GM-specific codes.

What would be symptoms of the wave plate failures?

I am coming to this forum’s experience for diagnosis because it’s clear from everyone’s experience that the shops are not figuring it out and I’d rather direct the fee cash towards parts.
 

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Before you do ANYTHING else, I have an easy, free suggestion that may potentially change the driving dynamics and automated shifts.

Disconnect the battery and for added added benefit, pull the transmission control module fuse. Let that sit for a bit to clear the TCM memory.
Reconnect everything and start driving around. It's going to be a little rough at first, but give it 48-72 hours of mixed driving.

These "learning" TCMs can basically get bad memory data overtime, especially if you have different drivers using the vehicle.

Try that and report back!
 

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Discussion Starter · #6 ·
Before you do ANYTHING else, I have an easy, free suggestion that may potentially change the driving dynamics and automated shifts.

Disconnect the battery and for added added benefit, pull the transmission control module fuse. Let that sit for a bit to clear the TCM memory.
Reconnect everything and start driving around. It's going to be a little rough at first, but give it 48-72 hours of mixed driving.

These "learning" TCMs can basically get bad memory data overtime, especially if you have different drivers using the vehicle.

Try that and report back!
Will do TODAY and report back.
 

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Discussion Starter · #7 ·
Here's a thread you will be interested in reading: Wave Plate--Any early signs to watch for? A search of the forum for "wave plate failure" will get you to others.
THanks for the link! I am not feeling any of the "bucking", so hopefully that's a good sign.....
IS it possible to replace the TCM and waveplates without removing the tranny?
 

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IS it possible to replace the TCM and waveplates without removing the tranny?
People have done both before. You'll find threads in this forum about how those jobs were accomplished if your search skills are any good - keywords like "replace TEHCM" and "in car waveplate replace" should work. (The TCM is integrated with the TEHCM.)
 

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People have done both before. You'll find threads in this forum about how those jobs were accomplished if your search skills are any good - keywords like "replace TEHCM" and "in car waveplate replace" should work. (The TCM is integrated with the TEHCM.)
You can replace wave plates in an Acadia without dropping the tranny? News to me. Interesting.
 

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You can replace wave plates in an Acadia without dropping the tranny? News to me. Interesting.
There has been at least one person on here that replaced them without dropping the cradle. Most likely done out of desperation. I recall seeing the pics and just shaking my head.
 

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There has been at least one person on here that replaced them without dropping the cradle. Most likely done out of desperation. I recall seeing the pics and just shaking my head.
That member did it by just lowering the left side of the cradle enough to access the clutch drum. Using member name 'Keydiesel" in an advanced search will get to the thread. Keydiesel is reportedly an ASE-certified GM tech. They own (or work) in a shop by the same name somewhere in MI. I think a few other members have followed their procedure with success.
 

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The shop that replaced the wave plates in my 2009 Acadia said theu did it without dropping the tranny. I did have to bring it back due to the laminated disks (and replace them again a few years later), but the original repair has lasted over 70,000 miles.
 

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Not sure this helps but I just got back from having my Acadia (2015) serviced, I was having similar shifting issues you described, but not the engine temp. Mine was bad transmission fluid and after they flushed it, they had to reprogram the transmission control module. Noticed a huge improvement as soon as I started driving it home.
 

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Discussion Starter · #15 ·
GREATLY appreciative for all suggestions and comments!!
Tried the battery disconnect and TCM fuse pull, no effect.
Trans fluid is new due to torque converter replacement 5k ago.

With the reserach from the additional links everyone provided I'm leaning to the TECHM replacement. Does anyone have the PN for it for a 2016 Acadia? I'mm having trouble finding it, even within my AllDataDIY subscription.
 

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Does anyone have the PN for it for a 2016 Acadia? I'mm having trouble finding it, even within my AllDataDIY subscription.
Search the 'net using keywords "6T75 TEHCM" and you'll probably find it. The 2015 Acadia transmission will require a Gen2 TEHCM.
 

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Discussion Starter · #17 ·
Being that my 2016 Acadia AWD has the 6T75 Gen2 that is without the membrane pressure switches, what needs to be replaced to correct the delayed shifting situation? Do I have to replace the entire valve body?
 
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