When the dishwasher door latch does not operate as it should, your machine will not run. This can be a major annoyance but should also be an easy thing to repair. The latch serves two purposes. The first is to pull the door tight and keep it closed to prevent water leaks; the second is to activate the safety switch. If you cannot start your dishwasher when the door is closed, the door latch could be at fault as well as the safety switch. The following four steps will guide you in determining which of the two items is defective.
Step 1 - Test
The first thing you need to do when working at a dishwasher door is to TURN OFF THE WATER supply, as the water will spray out the minute it is started. To test the switch, you need to find its location by looking at the type of latch used and where it's placed on the door. The switch will be inside an opening at the top of the door opening where the latch lines up when closing the door. By depressing the switch with an object of similar size and shape, if the dishwasher does not come on, the problem is very likely to be the safety switch and you will need to be replaced. If any noise comes on you can assume electrical activity within and proceed at checking the latch itself as being the source of the problem.
Step 2 - Inspect the Latch
If the problem is the dishwasher door latch, the next step is to closely inspect it. Sometimes food particles or other foreign debris can become wedged inside, making it hard to open or close. If it's large enough or if enough debris is present, it will keep the door from closing properly and stop the dishwasher from working altogether. So, if there's anything lodged anywhere in there, it has to be cleaned out and then tested again to see if your problem is still there.
Step 3 - Lubricate
On some models, the latch will get its rotating movement from a pivot pin in an area where the dirt can accumulate and impede the movement or interfere with it. A spray of industrial cleaner such as nut or bolt loosener would probably get the lever moving easily again, after which you should give an additional spray with a good penetrating lubricant. This can be found easily at your local hardware store. While spraying, use a rag or your fingers to move the latch back and forth so the lubricant gets into all of the moving parts.
Step 4 - Check the Strike Plate
The strike plate is located on the dishwasher itself and is the part that the dishwasher door latch grabs onto to when it's closed. If the strike plate is out of alignment, the door will not close properly. To test, visually appraise it for any abnormalities; if the strike plate is bent in anyway, is loose, or out of alignment, it will need to be readjusted to its original shape and location within the door frame opening. If it's bent, it may have to be removed, straightened out with the proper tools and reinstalled, or it may even need to be replaced. While re-tightening into place, you can operate the door closed while watching carefully to see where the latch hits the plate so you can adjust as needed.
When all else fails, simply replace a defective door latch with a completely new one, matching you individual make and model.