Dryer will not shut off:
Located in the control console of the dryer the timer consists of a small motor connected to a series of gears that rotate cams, which turn electric contacts off and on inside the timer. The timer contacts control the dryer motor as well as the heat circuit and the timer motor itself. A defective timer motor or a defect in the timer's electrical contacts can cause the timer motor to fail and the timer will need to be replaced. The contacts can be checked for continuity with a multi-meter. This test should only be made when the dryer is unplugged. Another test u can do is observe by eyesight and see does the timer advance or is it stuck on one cycle?
1. On gas and electric dryers that have an "Auto Dry" cycle, the cycling thermostat
is often used to advance the timer as well regulate the drum temperature. Essentially, thermostat will alternately turn on the heat source or the timer motor when the temperature has been satisfied. To check this thermostat, you will have to check for power to the timer motor with a multi-meter, during a cycle. This is a live voltage test and caution should be used.
2. Some dryers will use a cool down thermostat
to tumble the clothes without heat, at the end of the dry cycle. Power is routed through this thermostat to the drive motor to keep it running until the drum temperature has dropped to a specific temperature. If this thermostat fails it can cause the drum to turn indefinitely or until the door is opened. You can check the thermostat for continuity with a multi-meter. This test should only be made with the power removed from the dryer.