Thermal fuse keeps tripping on dishwasher KUDS02FRSS1

[nelaco]

Hi everyone, my dishwasher keeps tripping the internal thermal fuse in the control panel.  I've replaced it with a new one along with the wires a while back, as well as the control panel and motherboard.  It ran normally for a year or so but now it trips every few minutes.  At first it was only when hot so I thought maybe it was the motor in the door vent was not working, but now it is about every 10 minutes or so. When I open the door to push the start button to get it going again, no steam comes out.  Diagnostics test completes without any issues.

What do you suggest I test next?  Thank you for your help!

 

2006   KUDS02FRSS1

[16345Ed]

2 hours ago, nelaco said:

  It ran normally for a year or so but now it trips every few minutes

Trips every few minutes? How many thermals have you replaced?

Edited May 8, 2020 by 16345Ed

[16345Ed]

That harness With terminal block HAS to be changed with fuse or it will continually blow. 

[nelaco]

It resets itself once it cools down and then power is restored.  The harness was replaced as well.  This is my 3rd fuse.

[16345Ed]

I have never known those thermal cutoffs to be resettable?

We are talking about this correct?

Part number: W10258275

[nelaco]

Correct, that's the part I am referring to, but, I could be wrong and what's resetting is something else.  Aren't these thermal fuses bi-metal?

[Budget Appliance Repair]

1 hour ago, nelaco said:

Aren't these thermal fuses bi-metal?

That is a one time thermal cutoff, (maybe a bi-metal but not designed to reset, designed to stay open on failure and be replaced after the fault for over heating has been corrected).

[nelaco]

ok, thank you Sensei.  So what's tripping then?  It stops mid cycle a bunch of times.  All lights go out, but then after 5 minutes or so, power is restored and when I hit "Start" (it flashes when it trips and power is restored) it keeps running normally...until the next "outage".  Diagnotics runs properly.  Thank you again for helping.

[16345Ed]

Check heating circuit. May be tripping when heater energized. 

[Budget Appliance Repair]

@nelaco Have you checked the wiring in the junction box where the main power cord comes in and connects to the dishwasher wiring?   You could have a loose wire nut and be loosing power under a load when the bad/loose connection heats up.

May need to remove the control board and remove the board from its plastic housing and look for burnt solder connections on the main power connection terminals and/or relays on the control board.

EDITED TO ADD:  I just noticed you already replaced the Control Panel, (do you mean the touchpad/console assembly), and Mother Board, (meaning the main control board that the thermal fuse is attached to?).

Edited May 9, 2020 by Budget Appliance Repair

[nelaco]

WIllie, thank you again for helping!  Yes, I replaced the Control Panel twice in the last year (first one must've been defective), AND the motherboard.  This was due to all lights flashing and it's been working fine until the last month or so.

I just checked all connections and they look fine.  The motherboard (about a year old), does show a little brown and the P3 and P4 terminals show signs of overheating.  

I ran 2 diagnostics just now and they both finished in 16:15 minutes without any issues, but I am not exactly sure how to really know if they found any issues.  All the lights go out at the end of the test.

I then started a "Heavy Duty" cycle and it was running fine for 17 minutes and then the same thing happened...stopped and all the lights went out but 5 minutes later the "Heavy duty" come on and the "Start/Resume" light was flashing.  I hit "Start/Resume" and closed the door and it ran again for 5 minutes. Three minutes later it gave the option to resume the cycle. This usually continues until it finally finishes the cycle.

 

Anything else you can think of?  Do I need another motherboard?  The one I replaced last year was new from Amazon made by Whirpool. 

I see them in Amazon USED for $76 and new by "ForeverPro" for $309.  The part number is W10084141.  If this is what I need to replace, any recommendations of where to get it from?

 

Thank you again!

[nelaco]

Well, I've decided to take a closer look at the board.  The wires at P3 and P4 were very hard to remove due to the heat they had been dealing with.  While pulling them, the plastic insulation fell apart, since it was all brittle.  On the back of the board, the soder looked fine but you can tell it's been overheating.  Is there a relay I need to replace?  I measured the resistance of the heating element and it is at 23 ohms, which is within specs.

What causes this issue....just cheap motherboard parts?  Fortunately I am able to return this motherboard, but I would like to buy a quality one and move on.  The first one lasted 14 years!

 

 

[nelaco]

I just read somewhere that it could be the circulating pump.  When they start going bad they pull too much current and cause the board to fail.  Any way of testing the motor?  The dishwasher is 14 years old after all.  

[Budget Appliance Repair]

Doubt that it is the circulating pump - the overheated connectors happen from loose connections.

I was thinking maybe the door switch is going bad but I don't think all the lights would go out if that were the case - it sounds like you are completely loosing power to the dishwasher.

You said you checked all the connections - how about the wiring in the power cord junction box down at the front right corner behind the kickplate?

[nelaco]

Thank you WIllie. Yes, I checked the wiring by the power junction box behind the kickplate and no signs of overheating.  They feel nice and tight.

The door switch is new as well since I had replaced it when this problem started in case that was it.

I went ahead and replaced the female connectors on P3 and P4 with new ones.  I had done the same 19 months ago.  It is running perfectly again.  I guess I'll just have to keep doing this every time I start seeing this problem again.  This is why I think the pump (or something else) could be causing this issue since it ran fine for the first 12 or so years of its life.  Something must be drawing more current than it is designed for, causing the overheating of those connectors.  I just can't figure out what it is.

I am happy now....we'll see for how long.  I wouldn't mind replacing the unit with a new one, but for what I've researched, looks like they are even worse than mine from back in 2006.

 

Thank you again!

[nelaco]

Well, 10 days later started happening again. Any ideas on what to check next?  Again, it is terminals P3 and P4 the ones that melt and need replacing.  I believe they are part of the heating circuit but I don't know if anything else uses it or not.

Motor is not any louder than it used to be (unless I got used to it over the years).  

 

Please let me know if anyone as any suggestions.  I wouldn't mind buying a new dishwasher at this point, but once I start reading reviews sounds like they not lasting as long as the old ones.  Rather just fix this one if possible.

Thank you in advance!

[Vance R]

P3 and P4 are for the heater circuit. The heater should 10 to 30 ohms. Check the connections at the heater and temp bi-metal. Also check the wires. Next is to make sure the terminals on the board are clean and the solder connection on the board are good.  Not sure if you have replaced those terminals in the harness.  If you need to replace those terminals, use high heat terminal not ones from hardware store or auto parts store. Check the wires for heat damage.

[nelaco]

Thank you Vance R. Yes, I've done all of the above except I've replaced the terminals on the harness with regular one.  I had no idea they made "High temp" ones.  Thank you!  I'll try that next.

[topice]

I was just following through your post.  What was the final cause of the problem ?