Good morning! I've received great information from these forums and subsequently ordered parts from the sponsors; great service!

Anyway, our dishwasher just started emitting a LOUD noise that can best be described as an alarm clock buzzer or constant hum; it could be a grinding noise, but that's a bit of a stretch. The noise starts when the wash cycle begins; the noise is not present when filling or draining.

Any suggestions or where to start diagnosis?

Thank you,
Ken

I've got the same model dishwasher with the same problem. Has anyone been able to determine the cause of this?

This is identical to my Kitchenaid. Here is what I did.
Disconnect water and electric,slide unit out and tip it down on the front door for access. Separate the electric connector at left side of motor The motor has 1 retaining bolt above the white heat shield remove it. Twist the motor counterclockwise and wiggle it. Note the position of the plastic housing and mark it relative to the casting on motor there should be arrows on each piece.
Back side of motor you should see the cooling fins. Carefully stick plier handles into hold in place while you unscrew (counter clockwise) the impeller. (might need pliers) Remove plastic housing. At this point you will see some corrosion if it is the seal and bearing. Mark the positions of the front middle and back castings. Remove the four screws,slide off the front casting,if bearing is stuck install the impeller and gently tap on it while holding casting.Remove the retainer between bearing and armature, put a deep socket over shaft on bearing and tap bearing down about 1/8 " That allows you to clean shaft of all corrosion so you can remove and install new bearing file shaft to clean finish with some emery cloth remove bearing New one can be purchaed at any bearing company #608Z Replace seal as well.

Good luck