When troubleshooting ice makers, there are a number of different things you will need to inspect, check, and look out for. An ice maker could suffer from various problems that would prevent it from ejecting ice.
Ice Cube Ejector Gear
Read your refrigerator's instruction manual for directions on how to locate the ice cube ejector gear. The ejector gear controls when the ice is released. This is made out of two plastic cogs that must mesh together. If there are any problems with these gears or if they have worn out then the entire ejector gear will need replacing.
Normally, it's possible to replace the ejector gear only on component models. If you have a modular unit, replacing the individual gears may not be an option and you may need to replace the entire control module.
The ejector motor is used to control the ice as it is released. If you can replace individual components, it should be possible to test and replace the ejector motor individually if required.
Dismantle your ice maker and locate the ejector motor. Disconnect the wires and inspect the terminals. If any terminals are corroded, these will need to be replaced or cleaned.
Using a multimeter, check the motor for continuity. To do this set, the multimeter in resistance mode and check that the motor is a complete circuit. The motor should show resistance of between 500 to 600 ohms if it is healthy. If it shows infinite (∞) resistance, the motor is faulty and will need replacing.
Ice Mold Heater
The ice mold heater is the device that heats the mold so that the ice will fall out. This should be located just under the ice mold trays and is connected to two wires. Mark which wire goes where, and then disconnect them.
Use the multimeter to measure resistance and check the continuity of the heater. The normal range should be between 60 and 90 ohms. If the heater is showing up with zero resistance or is infinitely resistant, the heater is faulty and needs replacement.
The thermostat controls the temperature of the ice maker and is located at the bottom of the support box. Use the multimeter to test the resistance of the thermostat at room temperature. The meter shouldn't give any reading, due to the open circuit. Then turn the freezer on for 20 minutes and run the same test again. This time the reading should be 0.