2015 Caravan 50K. Wife had a slow speed hard lock vibration in steering wheel. Checked it stopped and felt vibration at 3/4 to lock on both pavement and grass. No pedal vibration when rolling. Very intermittant noise when driving. She had the dealer look at it and they say warped rotors. I have never had rotors cause a steering vibration when the vehicle is not moving. Never had bad rotors that didn't provide feedback thru the pedal pulseing. Attribute road noise to new gas milage tires ran at higher pressure and interacting with different road surfaces. I thought pump or steering assist rod but dealer has her convinced to change rotors @.$300. Thoughts? I pulled wrenches for many years back when cars like people were not so sensitive.

 

Would you say when the car is not moving, and you turn the steering wheel 3/4 to lock either way, you feel vibration in the steering wheel? Or is the vibration felt when steering wheel is turned in one direction only? I'm a bit troubled that the dealer did not say which rotor was warped. You can check for a warped rotor by removing the road wheel and reading the run-out of the rotor. You'll need a dial indicator and a mounting device (borrow from a friend or buy at Horrible Freight).

 

Car not moving. Vibration is more pronounced on left turn. Did it on pavement and grass with no change in vibration. Ruled out tire sticking on pavement. I think it is either the ps cylinder or the pump.

 

the vibration can't be brake related if it occurs when the brakes aren't applied. bad front rotors will transmit into the steering wheel during a high speed brake application.

I have heard of worn spool valves in the rack and pinion bleed into the wrong circuit and cause a shimmey. A 2015 with 50k is pretty new for a worn rack to occur. Any p/s leaks or p/s noise? The racks are expensive so I wouldn't want to "steer" you in the wrong direction...internet diagnosis is kinda hard.

 

Agreed... with the wheels not rotating, you won't know about warped disks. The left/right difference has to be a clue.