: need a diagnosis

09-02-05, 11:35 PM
OK, I tried this question before and couldn't get an answer. I'm going to try 1 more time before I bring it to the dealer.

While cruising on the highway, 5th or 6th gear at very light throttle I get a vibration. It rattles something in the sunroof area so bad that even with the radio on it bothers me. The whole car vibrates noticeably .It goes away if I get off the gas, or get on the gas more than a little. Doesn't matter at what speed so....

Can't be tires because the noise goes away when I get off the gas 100%
Can't be an alignment problem for the same reason
Can't be a drive shaft balance for the same reason

It happens at very minimal torque on the driveline only. Anyone else have this problem?

09-02-05, 11:42 PM

I know you believe it "can't" be a drive shaft balance issue - but I cured this problem by indexing the drive shaft as described on the .faq (there is a TSB on the process).


09-03-05, 01:29 AM
Why cant it be the driveshaft issue? Even if you get off the gas, the driveshaft is still spinning....

Do you have the bushings in your car? Did is start when you had those installed? if so, check to make sure your rear springs are seated properly. When you are on the gas there is a weight shift to the back (even though its very low). Just a thought!

Other than that, I say dealer....


Lindsay Cadillac
09-03-05, 06:58 AM
If it goes away when you let off the gas it almost has to be driveline related. As WW already said there's a TSB on indexing the driveshaft... It could be in the transmission or in the diff/axles.... You're going to have to get a technician in the car so he can feel it...

09-03-05, 08:09 AM
sounds driveshaft related. There is a bulletin out for this. They RE-INDEX the prop shaft. If this is incase the problem.


Lindsay Cadillac
09-03-05, 08:46 AM
FWIW you can find that bulletin here http://www.cadillacfaq.com/faq/tsb/data/04-04-17-003.pdf

09-03-05, 03:52 PM
Like mentioned above, The DS is still spinning when you let off the gas, if it was a DS balance issue, it would still do it when you let off the gas, and would still do it when I got on the gas, also it would only do it at a particular speed, here is can be at 60mph, as easy as 120. I drove the car again today and now its not doing it as bad in 5th gear as 6th, so I am leaning toward some kind of transmission problem.