Your back glass vibrates? Are your windows open?

 

Go back to the dealer and tell him to swap out your rims and tires for ones from another truck. I changed to Michelin and my vibration went away. Had the same thing right around 40-45mph it would vibrate. Those HPs SUCK!
BTW I live in the mountains so my MDS is almost never on and I would still get the vibration going up hill or down hill, round corners in straights etc...And of course the speed limit around here is mostly 45....Argh!
Go to the dealer three times and then let them know you are going to get into the lemon law issue. But heck my rear window never vibrated like that. Maybe a drive shaft issue?

Another thing I would do is to put about 50 psi in the tires and run it up to 45. If it still vibrates (at 45) it isn't the tires. Then let the air back down of course.

 

Take it to a different dealer. request the tech goes for a ride while you are driving to show them the issue. Get familiar with your State "lemon law" and follow the requirements of the law. Document everything you have or will do.

 

What a mess. New vehicles are way more of a pain then old ones. But anyway, i ran it in 5th with the tow haul on and that does kill the mds. The vibration and sound was gone. So i do believe it is the mds. Do you guys know if that can be fixed or is it a big problem ?

 

Congrats on narrowing it down.

I would take it to a different dealer and show them, if it is that bad they can not deny it.

Or, buy a tuner, disable MDS and call it a day.

 

Can you help me out on a tuner and how to disable the mds ? Is it going to kill my gas mileage ? I plan on switching to 4.10 gears anyway.

 

Killing the MDS and going to 4:10s from 3:21s is going to kill your MPG one way or the other. Why do you want to go to 4:10s? Are you towing?

 

How do they go about fixing the mds ? Do they have to put a new motor in ?

 

It may be as simple as flashing the computer. I can't remember the TSB number but their was one out a year or so ago for drivability issues dealing with the mds.

 

Do you have any nerf bars???? Some of them mount to the rubber mounts where the body mounts to and alters the tuning of the rubber mounts. Maybe try taking them off and seeing if it gets better.