Mixer goes really fast then stops

First thing, check the Hall Effect Sensor (part # 9703312) to make sure that it is seated snugly AND properly!  The Hall Effect sensor measures the speed of a tiny rotating magnet and basically tells your mixer how fast it should rotate.  I was experiencing the same problem that many others have described here--my mixer would go really fast no matter what speed I put it on and it would shut off after five seconds. I came to the FixYa site and saw that one solution that seemed to work was to replace the Hall Effect sensor.  So I went to a local hardware store and purchased a new Hall Effect Sensor for about $13.  After I replaced the "defective" sensor, my mixer still did not work.  So, I started experimenting with the three prong orientation of the control board--this can make a big difference. After a little trial and error, I found the correct orientation for the sensor and my mixer worked good as new!  But I was curious to see if the improper orientation was the cause of my original "defective" sensor.  So I put the "defective" sensor back with the proper orientation and THIS ALSO FIXED MY SPEED PROBLEM! There was nothing wrong with my original Hall Effect Sensor at all--it simply was not snugly or properly seated!  I'm not sure how it happened--possibly over time the sensor prongs may have become unseated from the vibrations of running the mixer on high speeds--but my original Hall sensor was not seated properly or snugly.  So before you run out and buy a new Hall Effect sensor make sure that the original one is not only snugly seated but also properly oriented!  If I knew how to add digital pics, I would have put pictures in my comments to clearly demonstrate what I found.  Unfortunately, I am not sure how to do this.   To sum this up: 1. Download the parts information and diagrams from the Kitchenaid site and find the Hall sensor (part # 9703312).  2. Make sure that the Hall sensor is firmly attached on both ends.  The actual sensor should be located next to a tiny magnet and this end needs to be securely seated.  And the other end of the Hall effect sensor has three small prong holes which also need to be firmly and corrected seated to the control board! Bottom line, my mixer is working like new and I put the original Hall Effect sensor back in the mixer. I'm going to hold on the new one as a backup...you never know.

I replaced the Hall sensor and fixed my problem. Not sure the part number, but if you call a parts place, they will know. It was fairly cheap as I recall.

The partselect.com web site has good info if you have the model No. information. I plugger in my model KD2661XMC and came up with a potential lead --- The Speed Control Switch. The cost of the switch is $83.00, and I am seeking a second opinion before buying the part, simply to verify that it may be a solution.
Has anyone tried the KA website??

After hit and-miss-take-apart I discovered a simple solution to tweak the Hall effect sensor. I took the two klystron magnets from a trash microwave and gently passed them by the aluminum body of the KitchenAid just between the slide control and the ice cream gear outlet . . . and voila: the rpm is constant and uninterrupted. I'm to assume the hall effect sensor-- uses permanent magnets to provide the transverse field for the current flow and subsequent distorting and consequent area voltage difference through the active current region. The magnetic field must come from the electric motor axle which seemed to mount something akin to a magnet.

My wife has a 450 Watt KV25GOXMC Professional 5 mixer that jumped to the highest speed while kneading bread. She had it set on #2 speed setting, and the stand was vibrating. I tried using it later, without anything in the bowl, and it worked fine on all speed settings.

I opened the top bracket of the mixer and examined the main board and hall sensor. The plastic housing of the hall sensor was not holding tight to the mixer body (some motion could occur). I took some aluminum foil, folded it to a desired width, and inserted it next to the plastic housing (on the rear side closest to the rear of the mixer). It allows for no further movement, and is very tightly wedged such that it should not come loose. I could remove it if I used needle-nose pliers.

I re-attached the top bracket and gave it a movement test. All speed settings were under control while the movement continued.

I will update this note if I have any problems with this mixer.

The Hall Sensor worked for me as well. Cost was less than $10. First step is to download parts manual from Kitchen Aid site, find part number and then order part from local repair shop. Remove top cover from unit by removing 5 screws, replace sensor, and mixer should work like new.

I replaced the speed control assembly on my Kitchenaid mixer and it had no effect. KA customer services will not help and only tells you to take the mixer to an authorized service center.

Taht is the Hall sensor, 9703312 available from total service.

I wiggled the hall sensor wire and it fixed itself. God maybe???