If you washing machine is overfilling, taking too long to fill, or not filling at all, the cause could be a defective water inlet valve. The valve can fail either electronically or mechanically. To determine if the valve has failed electronically you should test each valve coil for continuity which will indicate weather or not a continuous electronic path is present. You can choose from a variety of multimeters to preform the test (both analog or digital meters). When using an analog meter, first rotate the range selection dial to the lowest setting for ohms of resistance, then calibrate the meter by pinching the probes together while adjusting the needle to read zero. When using a digital model again rotate the dial to the lowest setting for ohms of resistance, or resistance with tone if your meter has this option. Before you begin make sure the inlet valve has been removed or isolated from the appliance. Now use a probe to touch one terminal of the coil you’re testing, and the second probe to touch the other terminal if the meter. If the meter reading shows a result between 500 and 1500 ohms of resistance the coil has continuity, however if the meter does not move, or the digital display doesn’t change significantly there is no continuity which means the valve has failed electronically and will need to be replaced. Determining if the valve has a mechanical defect can be more difficult. First confirm that there is sufficient water pressure to the inlet valve. To determine this, shut off the water supply, disconnect the hot and cold-water supply lines from the inlet valve, and hold them over a bucket or sink. Then turn the water supply back on and observe weather or not there is a strong flow of water jetting out of the lines. A weak flow indicated low water pressure which could be caused by a problem with the water supply lines, or the valves. Low water pressure prevents the inlet valve from closing properly resulting in over filling and water trickling into the tub when the washer is not in use. However, if the water flow coming out of the supply lines is strong, the inlet valve itself is probably restricted and will need to be replaced. Trying to clean out an old valve is not recommended due to the risk of part failure after repair.