Steering wheel vibration when autopilot brakes hard

[T3SLA90D]

I have an unusual kind of steering wheel vibration. It only happens when autopilot is on and autopilot brakes hard at moderate and high speeds (around 40mph and higher). No vibration if TACC brakes hard and autosteer is off. No vibration if I brake hard. The vibration frequency doesn’t seem the speed dependent. It almost feels like the lane departure vibration but more pronounced. I have lane departure warning turned off.
Service center changed my front rotors twice and problem not solved. Any ideas? Could it have something to do with the autosteer mechanism? Thanks

 

[DerbyDave]

Nothing I know of would cause this "sometimes". I assume you have a 90D? The vibrations should be consistent with any similar speed or slow down, unless antilock is kicking in most all the time only on autopilot. Next things I would check are the roundness of tires and wheels, but then again, the vibration should not only be on autopilot. Antilock issue???

 

[T3SLA90D]

Doesn’t seem an antilock issue as it doesn’t feel or sound like it.