You wouldn't even know your dishwasher had one until it isn't working. These little switches are tucked inside the control panel of your dishwasher and most times are a part of the door latch. The door latch pulls the door securely to the main body of your dishwasher and prevents water from leaking during a cycle. If your dishwasher doesn't start, it could be due to a faulty door switch.
How the Door Switch Works
When the dishwasher door is open, the switch is off.
Inside your dishwasher tub will be a metal or plastic prong. Close and latch the door. The prong will depress the door switch completely, and the circuit will close allowing the dishwasher to start. Check the prong to make sure it's not loose or bent, and it's properly activating the door switch. It is important to disconnect the dishwasher from its power source before attempting any repair. You can unplug the dishwasher from the outlet, remove the fuse from your fuse box, or flick the breaker switch on your circuit panel. This will prevent you from getting an electric shock.
What a Door Switch Looks Like and Where It's Located
Typically a dishwasher door switch is an inch long. It can be black or red and has metal prongs called terminals protruding from the body. Some door switches have two terminals, and some have three. The terminals can be a common terminal (COM), normally closed terminal (NC) or a normally open terminal (NO).
Switches with only two terminals will either have a COM and a NO, or a COM and an NC. Door switches with three terminals have COM, NC, and a NO.
Your dishwasher's door switch will be behind the control panel on the front of the unit. It may be necessary to remove the inner panel of the door first. You can do this by removing a few screws.
The screws at the bottom of the door are for the hinges. You do not need to remove the whole door for this repair. Once the inner panel is removed, you may find another smaller panel covering the back of the control panel held in place with screws or clips. By removing this panel, you will gain access to the latch assembly housing the door switch.
How to Remove the Switch
Carefully use needle nose pliers to pull the wires leading from the harness off the terminals. For door switches that have a locking clip, depress the lever as you gently pull the harness away from the terminal. Take your time while removing switches that are a part of the latch assembly or that have a bracket. If you rush and break the switch's housing, you will end up having to replace more parts.
How to Test Your Door Switch
- Set your ohmmeter to measure resistance at a scale of Rx1.
- Touch the metal tips of the test leads together and zero your ohmmeter by adjusting the thumbwheel in the front of the meter until the needles reads "0" on the scale.
- Touch one meter lead to the COM terminal and the other lead to the NO terminal. Do not push in on the actuator.
- Your meter should give a reading of infinity, meaning the circuit is open, and there is no continuity.
- Without moving the meter's leads, press down on the actuator until you hear a 'click.'
- With the 'click' of the actuator, the meter should produce a resistance reading of zero ohms. It means the circuit is closed and continuity is present. (You will only hear this click with a door switch with three terminals.)
- Keep the meter lead that is touching the COM terminal in place, but moves the other meter lead from the NO terminal to the NC terminal.
- When the actuator is released, you should receive a resistance reading of zero ohms.
- Now set your ohmmeter to its highest resistance scale and touch one meter lead to the NO terminal and the other meter lead to the NC terminal.
- The resistance reading between these two leads should be infinite.
- Finally, take a resistance reading from both the NC terminal and the NO terminal to any metal mounting hardware that is a part of the switch assembly. You should receive a normal reading of infinity.
Any readings that differ from the tests above are signs of a defective door switch that will need to be replaced. Replace the old switch with a new one, using the same process as explained above. Reassemble the inner door panel and reconnect your dishwasher to its power supply. Don't forget to replace your fuse or turn the breaker switch back on. Run your dishwasher through a cycle to make sure it's working properly.