If the ice maker is running but doesn't make much ice, water supply problems, a control board failure, a weak recirculation pump, clogs in the water distributer or a faulty cutting grid could be the cause. First, check ice cube thickness. If the cubes are thin, a clogged water filter, problem with the water supply or clogged inlet water valve will cause thin cubes. If your ice maker uses a water filter, replace the water filter to improve water flow to the ice maker.
If ice cubes are still thin after replacing the filter or your ice maker doesn't have a filter, check the ice maker's water supply. Unplug the ice maker and shut off the ice maker's water supply. Disconnect the water supply line and place the end of the supply line in a container. Briefly turn on the water supply and check water flow through the supply line. If water flow through the supply line is weak, have a plumber fix the water supply going to the ice maker.
If water flows through the supply line okay, check the wire harness connections between the electronic control board and the water inlet valve. Reconnect loose wires and repair damaged wires. If the water inlet valve wiring is okay, reconnect the water line and open the water supply valve going to the ice maker. Run the diagnostic test cycle described on the tech sheet to check the water fill process. (You can typically find the tech sheet inside the control panel or on the back of the ice maker. Make sure that you disconnect the ice maker's electrical power before accessing internal areas to find the tech sheet.) If the water valve opens during the diagnostic test cycle but doesn't fill the reservoir enough to trip the water level switch that indicates when the reservoir is full, then you may need to replace the water inlet valve. If you replace the water inlet valve and the reservoir still doesn't fill up, then a failed electronic control board could be causing the low reservoir water level.
If the reservoir fills up during the diagnostic test, a weak recirculation pump or clogs in the water distributer could be causing thin cubes. Run a cleaning cycle to clean deposits out of the water distributer so water flows freely across the evaporator plate. If ice cubes are still thin after the cleaning cycle, you may need to replace the recirculation pump because the pump isn't moving enough water across the evaporator plate to create thick ice cubes.
The ice maker produces less ice when chunks of uncut ice clog the cutting grid, so check the cutting grid for ice build-up. Replace the cutting grid if you find damaged wires or the wires aren't cutting the full slab of ice into cubes.
Finally, a faulty ice bin thermistor could be detecting a full ice bin when the bin isn't full. Refer to the tech sheet for temperature/resistance values and check the resistance of the bin thermistor using a multimeter and thermometer. Replace the thermistor if its resistance is off by more than 4,000 ohms.