Appliance Balance Switch: During the wash period of your washer, there is comparatively little stress to cause the appliance to move around on the floor. In the high-speed spin, a great amount of centrifugal force is build up in the appliance, and it is particularly noticeable if the clothes load is not evenly distributed around the washer tub. Many items such as a heavy blanket or coat could tend to concentrate the load on one side of the inner washer tub. Most washing machines are designed to take an off-balance condition with no bad effects.
In the UK it’s very hard to get circuit diagrams or repair manuals. I get many emails from people looking for repair manuals and wiring diagrams for white goods appliances, but they are only available to the trade. Even then they are commonly only available by opening a trade account, paying a subscription and logging online into a manufacturer’s secure technical support web site. Another common way the trade can have access to them is by subscribing to them on DVD, which isn’t cheap, and needs renewing every several months or so. Gone are the days when we used to buy the wiring diagrams and repair manuals in printed form.