, this dishwasher would work intermittently for the customer, meaning sometimes it would start, and other times it wouldn't. The customer noticed after much trial and error with the controls that if the door was slammed shut with the timer set for a wash cycle, it worked most of the time. But the customer was afraid the latch was going to break, so she did the right thing and decided to repair it.
Like most anything that requires a power source to function, the first place to look when it is no longer working is the electrical connection or power plug. Once you know it has power, it is a simple process of following the circuit until we find the point the electricity stops. But it isn't always that easy because we must remember, for electrical components to function, there must be a complete circuit for electrons to flow. Which means, just because we have power, doesn't mean we have an electrical circuit. For this reason, it is important when taking electrical voltage measurements to always check for voltage in reference to a neutral wire and not the frame of the unit.
While dishwashers have continued to evolve using new technology to provide for lower water use while maintaining or even improving their ability to wash dishes, there has been one function that remains constant on all dishwasher designs to date. They don't wash dishes with the door open. And because this is a constant no matter the unit we are servicing, it gives us a good starting place to look when our dishwasher refuses start.
On this dishwasher (like many others), the electrical circuit is a short path from the junction box, through the door latch switches and on to the timer. A quick check with my meter showed voltage through the door switch when the latch was closed indicating the switch was functioning properly. But this latch also contained a switch for the neutral return line requiring both switches to close properly in order for there to be a complete circuit for current flow. With the power disconnected, I did a resistance check of the switch and found an infinite reading in both the open, and closed positions. Because the switch never closed, current couldn't flow and the dishwasher would never start. Slamming the door seemed to work for the customer at one time, but by the time I looked at it, the switch was done for.
I removed the latch from the inner door panel and replaced it with a new latch assembly which also contains two new interlock switches. Reconnected all the wires to their respective locations and put the door back together. Once the power was turned back on to the unit, starting a wash was simply a matter of selecting a cycle, and closing the door.