Step 4 · Test Door Interlock Switches

The door interlock switches are safety mechanisms that prevent the microwave from operating when the door is open. Locate these switches, typically near the door latch. Disconnect their wires and use a multimeter set to continuity mode to test each switch. A good switch will show continuity when the switch is engaged (e.g., door closed) and no continuity when disengaged (e.g., door open).