Put it in neutral and see what happens to the vibration.

 

How many miles are on the car? First thing I'd try is tire balancing.

I might be suspicious of the axles as well, but try the tire balancing first.

 

I'd check an out of balance wheel first, then possibly wheel bearings, then even your CV axles. If it's truly high miles (say well in excess of 150K), I'd suspect wheel bearings.

But simplest things first. Get the balance on the tires checked.

 

Diagnosis will be easier when you separate the symptoms from the operational status. If the vibration stays the same when you are coasting, without the powertrain engaged, then balance would be your greatest possibility (or tread separation, out of round wheels as 2 examples). If the vibration does change when you go into neutral then you would suspect something like an axle or other things that would not be load related.
Sometimes two out of balance wheels can become synchronized where their individual "out of balance" conditions coincide and make the effect much worse, while at other times they could tend to offset teach other and make the symptoms much less obvious.

 

toyota sienna 2004 shuddering

 

It does not shudder when coasting. I have already tried that so I don't think it is the tires, bearings etc since they are still turning. Also, the car is shifting and driving normal at other speeds and within the same rpm range at which the problem occurs. If it is the transmission then it would could be the top gear only that has a problem. I have seen some videos on torque converter shudder and that may be the problem. Does anyone know about that kind of problem?
Mike

 

I kind of doubt it's the torque converter. They're not common problems with these transmissions. But how many miles do you have?

Out-of-balance wheels can act weird. I wouldn't rule them out just yet.

 

188675 miles. If it was the wheels why would it only happen when not coasting,

 

I have been looking into the possibility of inner cv joint issue but it seems strange that it would not happen on accelerating in other gears and speed ranges also.
Thanks,
Mike

 

Mine vibrated only under load and only at speed. Replacing the passenger axle fixed it.

 

My Avalon had a light shudder when lightly on the gas above 45 MPH. It would disappear on throttle lift. Never appeared below 45.

After chasing my tail a while, a complete trans fluid change fixed it. Not a drain/fill. I believe it was the torque converter lockup clutch slipping.

 

How many miles did this happen at? Good that it was able to be solved with a full change of the ATF. Was the ATF very old/neglected?

 

Hi Mike, I have exactly the same problem and mine is a 2000 Sienna with 160000 miles on it. Only vibrates when turning into the highest gear (?) in speed of 60-65 mph, under 60 it runs smooth and transmission works fine. Have you solved the problem? Looking forward to your reply.