99 Yukon Vibration

Hello,
being new to Automotive Forums let me say thank you all in advance and I think everyone here is great.


I recently bought a 99 Yukon 2WD 5.7 with 111,000.
at 45mph threw 65mph on and off the Yukon vibrates and shakes, it only shakes when you are light on the gas peddle. if you are heavy on the gas to 70mph or not on the gas at all (coasting to a roll) it is smooth. I have replaced the U joints balanced the drive shaft and replaced all of the shocks so far.
any help will be much appreciated.

Welcome to AF, what shakes?

The entire vehicle shakes, you can feel it in the pedals steering wheel and seat. If I forget and leave a cup of coffee sitting in the cup holder all of the coffee will splash out of the cup. between 45 and 65 mph

Any body have any suggestions? I am thinking maybe the TCC solenoid. or transmission. any thoughts? Pleassse

I'd be more inclined to be looking at driveshaft U joints, to start out here.

If you suspect the TCC could be the problem, lightly press the brake pedal when the vibration occurs. If the vibration goes away, it could be Torque Converter Shudder. By lightly pressing, I mean enough to make the brake lights come on but not enough to slow you down. This will cause the TCC to unlock.

//2000CAYukon

U joints have been replaced twice. the drive shaft has been balanced by a very reputable shop in the area.

the new ujoints are less than two weeks old and are now in need of replacing. I am not sure why they are being ruined so frequently.

How do you know they need replacing? Was the problem there before the original work?

Yes, You can hear the ujoints clunk when you come to a stop and then when you go again. the same way they were before I replaced them the first time.

I have the same thing happening...exactly. The only difference is that I had a misfire #6 cylinder. The dealer checked out the iginitionan it's all good. They said that they think the valve is sticking and ran some kind of cleaning solution through and added an additive to the oil. They say that this fixes the misfire 90% of the time.

However, I just drove it home and felt the same vibration at about 50+mph with light accelleration. The Check Engine light hasn't come back on, but I still don't know what could be causeing the vibration.

Anyone ever resolve this type of an issue? I see there is another person in the forum with the same problem.