8 speed trans, reprogram

Justin101714 · October 5, 2017

Don’t understand why am update to the transfer case would affect the transmission control module programming. Maybe the typed it in wrong on the repair order.....

The transfer case control module has nothing to do with shift quality. Maybe the reset your shift adapts as well. I don’t know

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spenpet · October 5, 2017

Don’t understand why am update to the transfer case would affect the transmission control module programming. Maybe the typed it in wrong on the repair order.....

The transfer case control module has nothing to do with shift quality. Maybe the reset your shift adapts as well. I don’t know

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I saw that on my receipt...and refer to an early post...I don't know all the codes and what not to question it...no idea where the computer's input is that controls all that stuff...so I just chalk it up to computer related...if it were my '71 and they said that, I would have a lot more questions...but it shifts way better now, so whether it is a typo or what, I'm pleased.

Aaron McCurdy · October 6, 2017

I also had my 6.2L 8-speed in last week and they diagnosed it similarly, they performed the re-learn procedure and now it seems pretty close to night and day difference. Main issue was in the morning shifting from 1-2-3 was very rough under light acceleration.... Now its pretty smooth.

Mileguru · October 7, 2017

Similar thread from a while ago with TSBs in it. See:

http://www.gm-trucks.com/forums/topic/202425-new-8-speed-software-update/page-1

16-NA-411 for a 6.2L with an 8-speed

16-NA-412 for a 5.3L with an 8-speed

16-NA-019 I'm not sure what this one is for

Iceman22 · October 10, 2017

Checking in with a re-learn success story. Wasn't really dealing with the rough shifts but I was dealing with delayed engagement. Before the re-learn when first turning the truck on and going from park to drive; I would press the brake, pull the gear selector into drive, get off the brake and then there would be a dead period where the tranny was in limbo like it was still in park. Then all of a sudden the tranny would engage and lurch forward.

Post re-learn the shift from park to drive is almost instant and the truck just smoothly starts to roll forward on its own after getting off the break.

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Truck916 · October 12, 2017

Initially it made an improvement on mine. My wife has been driving it to transport the baby so I haven’t been able to drive it much. Drive it today after 1000 miles and it’s much better than before, but it still occasionally does the 1-2 clunk and a clunk while braking a little hard. Going to take it in again just to make sure. Doesn’t seem a tranny like this will last 100k. It’s a disappointment when you really think about it. Spent over 50k on my first big purchase and it’s been a let down.

16 Denali 5.3 8 speed

quicksilver64 · October 12, 2017

I had this TSB done to my 2015 6.2L 8 - Speed about 2 months ago. It was great. I say was because it is back to misbehaving. Same behavior as mentioned. Slow speed, in a parking lot for example, it shifts hard up or down after letting off the throttle. Feels like it is about to break a U joint. It is a shame they cant make it "stop learning".

I love the truck. Highway driving is awesome. The trans performs well under aggressive driving, but that isnt practical in town, school zones, parking lots etc. It is frustrating me enough to consider a trade, but I really dont want to.

I am likely going to get a custom tune on it even though that voids the 100K drivetrain warranty.

Doug83 · October 14, 2017

I had the same problems as those here, and I had this update done yesterday. I hope it stays this way because it is shifting great.

Pearl2017 · October 14, 2017

I'm somewhat convinced the "rolling idle speed" map has something to do with this problem, maybe not the cause but the symptom. Almost every complaint I've read has something to do with light throttle shifting. Clearly from the stock left map you can see GM placed an RPM bump in the idle to deliver some power to the wheels while rolling. My experience with it was fighting the engine when applying brakes and getting a gear clunk now and then as I forced down the RPMS with power seemingly still being applied. Only reason I can think of for this setting is to make low speed trailer maneuvering more effortless with the throttle. The only place I found it was useful was crawling in a traffic jam as the truck powered itself along. The map on right is where it is set now and IMO works a whole lot better. My theory as to why this makes a difference is due to the very complex torque demand control model these E-trannies operate on. A slightly out of spec sensor or component may throw the learning system out of whack. When you reset the learning system it Forgets the bad settings it has learned. I know this doesn't help anyone not able or willing to change it themselves but someone at GM needs to do something about whats causing it which includes a method for troubleshooting/discovering the root cause.

spenpet · October 16, 2017

On 10/14/2017 at 4:26 PM, Pearl2017 said:

I'm somewhat convinced the "rolling idle speed" map has something to do with this problem, maybe not the cause but the symptom. Almost every complaint I've read has something to do with light throttle shifting. Clearly from the stock left map you can see GM placed an RPM bump in the idle to deliver some power to the wheels while rolling. My experience with it was fighting the engine when applying brakes and getting a gear clunk now and then as I forced down the RPMS with power seemingly still being applied. Only reason I can think of for this setting is to make low speed trailer maneuvering more effortless with the throttle. The only place I found it was useful was crawling in a traffic jam as the truck powered itself along. The map on right is where it is set now and IMO works a whole lot better. My theory as to why this makes a difference is due to the very complex torque demand control model these E-trannies operate on. A slightly out of spec sensor or component may throw the learning system out of whack. When you reset the learning system it Forgets the bad settings it has learned. I know this doesn't help anyone not able or willing to change it themselves but someone at GM needs to do something about whats causing it which includes a method for troubleshooting/discovering the root cause.

thank you for this....this is so far above my head, but if i interpret what you are saying is that GM put the shift points that benefit heavy trailing at low speeds and adversely affects daily driving at low speeds? if that is the case, it makes sense...but it still (if working properly) shouldn't slam gears, just rev higher prior to shifting...

Having said that, computers are a challange and don't shift (per say) by pressures and RPMs like non-computer driven trannys...(I hope that makes sense...but I am just a simple man! haha!)

Bunks · November 6, 2017

Night and day difference after getting this done on my 16. I still get the occasional odd shift but a lot better after the reprogram.

nluchau · November 6, 2017

On 10/14/2017 at 4:26 PM, Pearl2017 said:

I'm somewhat convinced the "rolling idle speed" map has something to do with this problem, maybe not the cause but the symptom. Almost every complaint I've read has something to do with light throttle shifting. Clearly from the stock left map you can see GM placed an RPM bump in the idle to deliver some power to the wheels while rolling. My experience with it was fighting the engine when applying brakes and getting a gear clunk now and then as I forced down the RPMS with power seemingly still being applied. Only reason I can think of for this setting is to make low speed trailer maneuvering more effortless with the throttle. The only place I found it was useful was crawling in a traffic jam as the truck powered itself along. The map on right is where it is set now and IMO works a whole lot better. My theory as to why this makes a difference is due to the very complex torque demand control model these E-trannies operate on. A slightly out of spec sensor or component may throw the learning system out of whack. When you reset the learning system it Forgets the bad settings it has learned. I know this doesn't help anyone not able or willing to change it themselves but someone at GM needs to do something about whats causing it which includes a method for troubleshooting/discovering the root cause.

PM sent about this Pearl!

65VetteC6 · November 9, 2017

Is this only available on 16'? I called and my 17 VIN does not show any bulletins so they said they can't do anything for me.

AaronIROCZ · November 10, 2017

I had the update done a few months ago and the truck is completely horrible!! I have the 16 6.2 with the 8 speed. My last issue is when at a stoplight making a right hand turn on red trying to pull out in front of heavy traffic in a tight window with around 1/3 throttle the truck just sits there and lugs and chugs like the PCM is applying an aggressive amount torque management. I then have to floor it to get the damn truck moving with me being in the middle of merging into the lane and traffic is now on top of me. I would have rather had the rough shifting over this issue.

chrispassas21 · November 10, 2017

If someone that has a 5.3L 6 speed transmission and did something like this please let us know. I️ am having problems downshifting either from 3-2 or 2-1 I️ get the clunk a good amount since I️ do mostly city driving. Very upset about that.

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