I have a 2009 Chev Express van with 1,300 miles I experience severe vibration in the front end and steering wheel at speed above 55 - 60 mph. It does not happen all of the time. A serviceman from the dealership drove it and did not experience it, so was unable to diagnose the problem. This has been going on since I first started driving it in September. I am beginning to regret buying GM vehicle. I would appreciate any information that would help me get this taken care of.

 

Go back again. Ride with the Tech. I have a wheel out of balance on my truck right now, along with a bad alignment, depending on how hard my truck decides to pull I don't always feel the wheel being out of balance. Point I'm making, maybe a wheel is out of balance.

 

BB
If it only happened while breaking, the front break rotors would be suspect for out of tolerance

 

Have you looked up "Death Wobble" in the internet or on youtube? Is this what you're experiencing? You said it was severe and this is what comes to mind as being "severe." Sometimes it starts on its own, but sometimes it requires a pothole or bump to start the vibration. I've seen stock Fords do this and it was COMPLETELY stock. People that lift their vehicles have a higher chance of running into this, but some stock vehicle are affected by this.

 

How old are your tires?
This could be new tires fighting old ones
how long did the vehicle sit?
check your anti-sway bar bushings

 

unplug the power steering asst. its a solinoid that helps auto correct, it gets in a loop and goes nuts.

Dont regret your Gm purchace