When I turn camera on, the lens makes a sound like a low-pitched alarm and it never goes off until I turn power on. Also, when I look through the viewfinder, the whole image is shaking in tune with the alarm. You can feel the camera shake with each beep of the alarm. I say "alarm" because not sure off a better way to descrdibe it. It's not high pitched, but something is obviously malfunctioning. It sounds as though something is stuck in the motor? Obviously it won't take a good pic because it won't focus either.
To help figure out what is at fault, first turn off the stabilizer (IS) and also switch the lens to manual focus (MF). Does the sound still happen?
If no sound, first switch the lens into auto focus (AF). If still no sound, switch back to manual, then turn the stabilizer on. With the stabilizer on set the mode switch to 1 and then 2.
Those are exact trouble shooting step to follow for sure. But the bottom line is something is very wrong. And, it is not a good candidate for repair so make sure you get a good estimate before you do that. Working used lenses are in the $200 range so that is the limit for a repair.
Thanks. I was curious because I just ordered a "gently used" one to use on my 90D. A friend had ordered (a used) one and when I tried hers, I liked it because it was so compact and lightweight so will make a great walkaround lens for butterflies, etc. I got a good deal on mine and am looking forward to receiving it. Good luck with yours!