Vibration in steering wheel
 

I have a 2018 Silverado and am having trouble diagnosing a vibration in the steering wheel. At highway speeds with the cruise set it is intermittent not constant and varies at certain speeds. Took it out today and set the cruise at 60 km/h, 70 km/h and 90 km/h at various gears. Gears 5 and 6 there’s no vibration at these speeds, gears 7 and 8 which are below 1500 rpm at these speeds there is a very noticeable vibration with the worst being at 90 km/h. Not sure what the problem could be hoping someone on here can help.

thanks.

I had a similar problem with my 2017 Sierra. Very randomly it would feel like I was driving over rumble strips for a few seconds. I took it to the dealer and they told me that GM had issued a TSB for this problem and fixed it under warranty. The TSB had the technician flush the transmission fluid. Since that was done I have not had the vibration issue at all.