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smcgrath67

Maytag dishwasher MDB7759AWS2 blowing fuse

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smcgrath67

I'll try this again, now compliant with the model number!  

Unsure how to delete my prior post about the same problem.

My Maytag dishwasher recently had a new control board installed by a local PCM.  It worked fine for a few weeks and then went dead.  I jumped the fuse in the control board and restored power to the appliance.  I replaced the fuse and it blew again on the first load of dishes, somewhere toward the end of the cycle, but I'm not exactly sure when.  The dishes were clean but the tub was full of water, if that helps.  I'm very much a beginner and unsure of what could be causing that fuse to blow?  I checked the heating element for resistance and it is within spec.  Any thoughts greatly appreciated.  Also, yes...I did use the new wire harness that came with the fuse.

Sean.

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Samurai Appliance Repair Man

Did either you or the PCM replace the wire harness that came with the TCO kit? The new wire harness and connector that comes with the kit is not optional. Everything in that kit has to be installed per the instruction sheet that comes with the kit. Loose wire connections are one of the causes for the TCO failing open. I’ve seen boards badly burnt beyond repair when this repair is done without using the new wire harness and splice block. 

5B1F6618-C823-41E5-9483-2EE0C6F363BC.jpeg

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smcgrath67

Thank you Samurai. the first time I did not, then the second time, after looking here and realizing my mistake, I did use the entire kit per instructions. I watched your video about the wires melting in the sound insulation...I'll check that. Like I said, the dishwasher will run almost to the end and then pop that fuse.

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Samurai Appliance Repair Man
19 hours ago, smcgrath67 said:

somewhere toward the end of the cycle,

This may correspond to the heated dry cycle. An easy way to rule out the heater circuit would be to disconnect one of the wires underneath the dishwasher to the heating element. Secure the loose wire so it doesn't touch anything and run another cycle to see if the TCO fails again. The downside is that this test will require installing a new TCO kit but you'll need to do that anyway to do any other troubleshooting, such as running the self test cycle. But if the TCO does not open again during this test, then you've isolated the problem to the heating circuit. 

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smcgrath67

Thank you, I'll give that a shot.  I did check the element for continuity and it was within spec.  Is it highly unadvisable to jump the fuse in order to run the self test cycle?

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Samurai Appliance Repair Man
1 minute ago, smcgrath67 said:

Is it highly unadvisable to jump the fuse in order to run the self test cycle?

I wouldn’t do this because until we figure what the exact problem is, you could damage the board. 

The element not having continuity wouldn’t cause the TCO to open but if the element has a path to ground, it would. Measure resistance from the heating element terminals to chassis with at least one wire disconnected from the element. Should read open. If you get any ohm reading, that’s a problem to troubleshoot. 

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smcgrath67

Thank you, sir.  As much as I'm looking forward to getting started with MST (right after the holiday craziness is done), being a noob is confounding!

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Samurai Appliance Repair Man
3 hours ago, smcgrath67 said:

being a noob is confounding!

This is a confounding problem even for experienced techs! But the heating element is the load with the highest amp draw so it makes sense to focus on that as the suspect troublemaker until it’s either confirmed or ruled out. The isolation test described above will do that.  

Also inspect the other wire connections on the board and door switch for any signs of overheating, charring, discolored insulation, etc. 

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smcgrath67

Will do, thank you very much.

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