Pulsing Vibration at 60mph.

[Tbounds]

2017 6.2 Denali 14k Miles  I have noticed that I get this vibration on highway. It seems to me it is like a shudder when engine is lugging like it needs a leer gear . 

I started leaving in manual position and every time it would start vibration I would done shift to 7 from 8. 

The vibration would go away , then shift back to 8 and it would shudder in cycles until either accelerated or or manually down shifted

anyone have this problem I believe it is transmission 

[Z45]

It could be the "Active Fuel Management" (AFM) and be a normal characteristic.    I have not noticed anything like this with my truck in 45,000 miles but then again this is the 3th truck I have had with AFM so I am don't notices it.

Edited October 23, 2017 by elcamino

[Tbounds]

Thanks it is annoying 

[Tbounds]

I spoke with my service  manager today about the problem and he was familiar  with it and said most of the time they can flush transmission ,replace filter and fill with full synthetic fluid and the problem goes away.

 

[orangedeluxe]

Did you ever get a solution to this issue?  I just bought a 2015 Sierra Denali and the transmission seems to vibrate around 65 mph like that.  I thought maybe it was the system switching from V4 to V8 but it’s not.