Harsh Shifting on the 8L90 Automatic Transmission

Retired Bob · February 9, 2017

TechLink article:

There may be several harsh shifting conditions on some 2015-2016 Silverado, Sierra, Yukon and Escalade models equipped with the 5.3L engine (RPO L83) or 6.2L engine (RPO L86) and the 8L90 automatic transmission (RPOs M5U, M5X). The shift conditions may include:

• Harsh 1-2 upshift (except for the first 1-2 upshift of the day)
• Harsh 3-1 downshift when de-accelerating to a stop
• Harsh downshift under heavy throttle apply
• Active Fuel Management (AFM) V4 to V8 transition harshness (6.2L engine only)
• Coast-down downshifts (6.2L engine only)

Skeeter McSkeet · February 9, 2017

Wonder why it would say 2015-2016 models, and have this "tip" below?

TIP: Due to the installation of the new TCM software, Bulletin #14-07-30-001 should not be used on 2015 model year vehicles. It will not allow for proper clutch learning.

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joshc64311 · February 9, 2017

Wonder why it would say 2015-2016 models, and have this "tip" below?

TIP: Due to the installation of the new TCM software, Bulletin #14-07-30-001 should not be used on 2015 model year vehicles. It will not allow for proper clutch learning.

Sent from my kayak

Goods question, is the 8l90 an 8 speed

Skeeter McSkeet · February 9, 2017

Goods question, is the 8l90 an 8 speed

Good catch, it is the 8 speed I do believe.

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joshc64311 · February 9, 2017

Good catch, it is the 8 speed I do believe.

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Did the 5.3l in 2015 come with the 8speed?

Skeeter McSkeet · February 9, 2017

Did the 5.3l in 2015 come with the 8speed?

I'm not positive on that, mines a 6 and so is my friends 15, both 5.3. I want to say it wasn't an option, but I can't for sure lol.

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TJay74 · February 9, 2017

2015 6.2 was 8 speed, 5.3 was 6 speed. 2016 6.2 was 8 speed, 5.3 was 8 speed if it was a SLT/LTZ optioned truck.

Crstfr · February 9, 2017

i got the 5.3 8 speed...its a 2016

nluchau · February 9, 2017

TechLink article:

http://sandyblogs.com/techlink/?p=7170

There may be several harsh shifting conditions on some 2015-2016 Silverado, Sierra, Yukon and Escalade models equipped with the 5.3L engine (RPO L83) or 6.2L engine (RPO L86) and the 8L90 automatic transmission (RPOs M5U, M5X). The shift conditions may include:

• Harsh 1-2 upshift (except for the first 1-2 upshift of the day)

• Harsh 3-1 downshift when de-accelerating to a stop

• Harsh downshift under heavy throttle apply

• Active Fuel Management (AFM) V4 to V8 transition harshness (6.2L engine only)

• Coast-down downshifts (6.2L engine only)

I have a 2016 Silverado 5.3 6 speed z71 with a Harsh 3-2 downshift when de-accelerating to a stop. Am I candidate for this????

HondaHawkGT · February 9, 2017

I have a 2016 Silverado 5.3 6 speed z71 with a Harsh 3-2 downshift when de-accelerating to a stop. Am I candidate for this????

No that's for the 8-speed only.

Cottonwoodguy · February 10, 2017

So after 7 trips to the dealership about shifting issues and having GM send an engineer to asses the situation and having them all say it is "Normal" for my truck to shift like crap in the low gears there is a TSB for it. What kind of crap is that? GM flat out lies to me for 8 months about the problem?

inspectorudy · February 11, 2017

I have a 2016 LT Silverado with the same issue of hard lousy shifts. The service manager took it for a spin and declared that it was "Normal". He said that this 6-spd tranny is a lousy shifter because of the mpg issue and they won't re-program it because it will lower GM's fleet mileage. I even bought one of the devices that eliminate the 4/8 cylinder shift and it didn't help at all. We ought to make them fix this lousy transmission. Anyone know how?