Six speed automatic tranny downshift question.

[Murf185]

New guy here. Just bought a 2017 Silverado 2 wd with the 5.3 engine. 650 miles on the truck and I've noticed a definite downshift feeling while stopping for a traffic light. Seems to be positive downshifting feel when rolling to a stop. Nothing alarming but was wondering if this is normal. Anyone else noticed this?

[Sierra706]

Happens to me occasionally. What size wheels do you have

 

 

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[6TEEN5.3]

I definitely don't think it's normal but most of them do it so it's common.

[Grumpy Bear]

It is part of the trans program to down shit each gear at a programed speed. We are all use to the old Turbo-Hydro XXX vacuum signaled kick down on partial throttle. and not going into low gear until the input shaft speed is near zero. The new computer controlled boxes set a speed range for a gear and keep things proactive. I believe it's called 'speed logic'. Not to be confused with 'Grade or Decent Logic' which they also have which prevents the truck from getting to much past the set point of the cruise control. Downshifting and using the motor as a compression brake. Not to worry unless it is unusually harsh. Anyway I like it. If you let off the gas further back from a stop sign in the country the truck will downshift as your speed decreased and you use less brake to stop. These autobots are smart today.

[Murf185]

Ahh, great info Bear. Thanks for the input. You are a font of knowledge. I'm really tuned into my truck as it's the first new vehicle I've ever owned. In my 59 years of age I've always bought new vehicles for my wife and kids. Now I have my own new truck for the first time in my life and I'm noticing everything all the time.

[Grumpy Bear]

Ahh, great info Bear. Thanks for the input. You are a font of knowledge. I'm really tuned into my truck as it's the first new vehicle I've ever owned. In my 59 years of age I've always bought new vehicles for my wife and kids. Now I have my own new truck for the first time in my life and I'm noticing everything all the time.

 

Your welcome. Knowing a thing is useless unless shared. Enjoy the ride.

[Thomcat]

New guy here. Just bought a 2017 Silverado 2 wd with the 5.3 engine. 650 miles on the truck and I've noticed a definite downshift feeling while stopping for a traffic light. Seems to be positive downshifting feel when rolling to a stop. Nothing alarming but was wondering if this is normal. Anyone else noticed this?

Don't screw with it yet. Mine did the same every now and then for the first 1K or so.....didn't think much of it figuring it was still in the adaptive learning process. hasn't done it since. But, I'm the only person who drives the truck......multiple drivers with different braking techniques may confuse the processor and keep it stupid.

[njk4o5]

Its the "chevy shift" - totally normal.

as is the "chevy shake" & "chevy seat slide"

[Orlando8]

My tranny was alittle goofy at first then after 500 miles or so she smoothed out smooth as glass. Part of the adaptive learning

[Boardmember]

My 6-speed isn't "smooth as glass," but it is an amazing and appreciated improvement over my old 8-speed.

 

I do experience what you describe on occasion but it's mild, not harsh like Grumpy indicates you should be aware of.

[earn3dale]

My 16 double cab was bad that's one of the reasons i trade it in for 17 ltz and it's much better'

[sk]

Try turning off Grade Braking. You can do this by holding in the Tow/Haul button on the end of the gear selector for about 5-10 seconds. You should get a message in the DIC telling you it has been disabled. Many people have said it helped with the tranny downshift points.

 

The only bad part is that you need to do it every time you restart the truck ...

[elementaltoad]

When was your 2017 built? Mine was built in March and had a funky shifting 6 speed. I took it in and there is a TSB for a Transmission calibration update. The new calibration is 24288803 for TSB 17-na-07. That fixed my complaints, I am still a little suspicious that it will hesitate or shift weird coming to stops again, but so far it has been much better, night and day different.

[jimbofoxman]

My 2015 does this, with only 13k on it, only had it for 2k. Just noticed it today. It's annoying! If you are going down a road say on a city street where you are just using slight pedal inputs to maintain 25 or 40mph and then maybe don't catch your speed right away and it drops below that, all of a sudden it downshifts and jumps about 200 rpm. Did it for me several times on the way home tonight, right around 27-28 and 37-38. It's not a big jolting downshift but it's noticeable. Seems silly to me. Wonder if their is an update for my 2015? Can't I just coast for Christ's sake?

[nluchau]

My 2016 5.3 6 speed has done this since day 1 with 11 miles on it.  I now have 14k miles and it still downshifts like you guys are talking about.  Wish I could ease the downshift feeling some as its really firm bumps when it does it coming to a stop.