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Whirlpool Dishwasher Flamed out K2 relay on Whirlpool control board

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quantum1976:
I started experiencing the dreaded blinking Clean LED (7 times) a few days ago on my 5-year-old Whirlpool DU1145XTPQ1 dishwasher. I popped the cover and took a digital multimeter to the top of the control board. I checked the continuity of the heater element (P6 and white-violet wire on the door switch) and it read 13 ohms. I then checked the continuity of the thermistor (P2-2 and P7) and it read 64K ohms (it was about 65F in the house).

It looked like both of these were fine so I assumed that it was the control board itself. I removed all of the cables and separated it from the plastic housing and made an interesting discovery. There was a nice burn mark (understatement) on the bottom of the board near the corner of relay K2 (see pic).

I'm ordering a new board from this website now. My question is, does anyone know what would cause this relay to burn out? Was this a freak occurrence or do I have a short somewhere that will blow the new control board when I install it?

Thanks,

Rich

Repair-man:
As the Tech Sheet points out, the K-2 relay is the heat circuit relay, so we would assume that some component in the heat loop is shorted or drawing unusual amps.  Heck yes, you better go over those parts with a fine-toothed OHm meter or prepare to join the "Board of the Month" club  :)


Main Control Board Part # 8564546


jumptrout51:
BOM CLUB  :2funny:

quantum1976:
Thanks for the reply Repair-Man. Any ideas what to look for?

I tried to check everything in-line with the heater circuit based on the Tech Sheet. I checked the heater element and high limit thermostat together (because I checked the wires at the control board instead of pulling the dishwasher out to flip it over) and it read 13 ohm. The tech sheet said it should be 10-30 ohm so it seems OK (not sure if the two components together are giving a wrong reading).

Next I checked the thermistor (also done checking the wires at the control board) and it read 64K ohms at 65F. This seemed off from the Tech Sheets spec of 48-52K ohm @ 77F and 12-13K ohm @ 140F. I thought this was OK because I was out of the listed temperature range.

Can you think of anything else I should look at? I have a few days to check things out until the replacement board arrives.


Thanks again for all the help,

Rich

jumptrout51:
Your hi limit thermostat may not be opening. I would replace it to be safe.
The thermistor is out of range. I would replace it also.
Once the board and these parts are replaced do a diagnostic cycle before running the machine.

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