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Bosch Dishwasher Burning Smell and no Operation

Model #SHU43C02UC/14icon, the customer noticed a very hot smell coming from the area of the dishwasher while it was in the middle of a wash cycle. After having a look inside and finding nothing, the door was again closed to allow the cycle to continue. The smell never dissipated and it was even accompanied by a slight popping sound until the display went out and the dishwasher stopped working as if the power was turned off. A check of the circuit breaker found it to still be in the on position, but then the customer decided to turn it off until the unit could be checked by a technician.

As I have talked about before, whenever an appliance simply shuts off and will not turn back on, it is time to figure out where we have power and where we don’t. Much like a lamp going out, the problem could be with the bulb, the switch, or even the plug or outlet, but the key is to break the lamp, in this case, into logical sections to check each component. If the light goes out, we may start with a new bulb because it is a common failure, but replacing parts without first verifying the lamp even has power may result in a miss diagnosis.

Dishwashers are not quite as simple as a lamp, but other than a few specialized components, are pretty close electrically. Given the fact this model is actually part of a manufacturer recall for a potential fire hazard, I could have started with the control, but instead thought it best to verify the unit even had power. And to do this, the best place to start is at the junction box behind the lower access panel. This is where the house electrical connection mates with the dishwashers wiring, and is usually about the easiest point to begin our search.

With the panel removed and the junction box cover set aside, I was going to check for voltage with my multimeter, but instead, found a whole lot of melted, and burnt wiring. After removing the damaged wiring and wire nuts, it appears during the initial installation, some 5 years ago, to much wire was pulled into the junction box making for rather cramped quarters. Through years of vibration, the insulation was rubbed off the dishwasher side of the black wire which started arcing to the frame and generated plenty of heat. This heat simply began melting everything resulting in a pungent odor, and finally burned through the wire cutting power to the unit.

It took a little work, but I was able to cut each wire back to good insulation, and with some new wire nuts, had the wires back together in no time. With the power turned back on at the breaker, the unit came alive and started working with the press of a button. The customer still needs to call and get the recall work done, but other than that, it’s ready to wash dishes again.

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