Dishwasher control board not delivering 120VAC to water valve, dishwasher not filling with water

[HockeyGuy]

Kitchen Aid dishwasher model KUDE40FXSP4 does NOT fill with water.

1. I tested the existing water valve by supplying 120V AC directly to it from an external source of electricity. The water valve works perfectly when supplied with the expected voltage - water from a hosed connection flows freely and at a very high rate.

2. I re-installed the water valve and conducted a multimeter test of the VAC delivered from the control board to the water value during a wash cycle. It delivers ~2.7VAC and NO water flows into the dishwasher unit. The water value is rated for 120 VAC so I replaced the control board. I installed it and there is still only 2.7V AC getting from the control board to the water valve. Water does not enter the dishwasher at all during a cycle.

3. There is no blockage in the tubes, and the copper water pipe delivers water at a very high rate as expected when not connected to anything.

4. A continuity test of the wire connector between the control board and the water valve is successful. 

Thought on what else might be the root cause?  

[jiaho]

you wanna try replacing the wire between the board and inlet valve?

 

[citizenX]

23 hours ago, HockeyGuy said:

Kitchen Aid dishwasher model KUDE40FXSP4 does NOT fill with water.

1. I tested the existing water valve by supplying 120V AC directly to it from an external source of electricity. The water valve works perfectly when supplied with the expected voltage - water from a hosed connection flows freely and at a very high rate.

2. I re-installed the water valve and conducted a multimeter test of the VAC delivered from the control board to the water value during a wash cycle. It delivers ~2.7VAC and NO water flows into the dishwasher unit. The water value is rated for 120 VAC so I replaced the control board. I installed it and there is still only 2.7V AC getting from the control board to the water valve. Water does not enter the dishwasher at all during a cycle.

3. There is no blockage in the tubes, and the copper water pipe delivers water at a very high rate as expected when not connected to anything.

4. A continuity test of the wire connector between the control board and the water valve is successful. 

Thought on what else might be the root cause?  

Did you check the float switch on the bottom of the tub (front right side) of the tub? From inside the tub, make sure the float cap freely moves up and down and there is nothing caught up underneath it. From underneath the unit, check that the float micro switch is working properly (with your ohm meter). It should be open (no continuity) when the float is all the way up and should be closed when the float is down. 

[WestTn]

What does your meter say the resistance value of that water inlet valve is? Or is there anything in the circuit that is out of spec? 

That circuit is more or less protected by a circuit breaker ( called a triac) Built into the control board. 

[HockeyGuy]

jiaho - That seems like a logical next step. I will try that. 

citizenX - Great suggestion. The very first thing I did in my troubleshooting was to check the float micro switch, as the original problem was the dishwasher was not draining. I pulled the original switch and confirmed that it was no longer working. I purchased a new one, which has been installed.  The installation of the float switch and its operation seems fine, as when I lift the float I hear the "click on" and when I lower the float I hear the "click off" from the micro switch. I might pull the float micro switch again and perform the ohm test on it to make this new one is ok (I don't recall doing this, and anything is possible).  

WestTn - I will check that and update in a bit.

 

 

[vee8power]

1 hour ago, WestTn said:

That circuit is more or less protected by a circuit breaker ( called a triac) Built into the control board. 

 

Check this out about how the board uses a triac to switch  neutral to a load:

 

[WestTn]

1 hour ago, vee8power said:

Check this out about how the board uses a triac to switch  neutral to a load:

 

This is exactly what I was referring to, I used the term circuit breaker to communicate I layman's terms.

 

I've watched that 5 times  

[HockeyGuy]

vee8power and WestTn,

I am not able to view vee8power's image, I am seeing the following instead:

"Sorry, we can't show this content because you do not have permission to see it".

I am also not able to post images of my own.

I am however able to view the image posted by WestTn.

 

[vee8power]

@HockeyGuy, I'm sorry, I forgot you are a DIY member, only pros and alumni get to see tech documents and webinars.

Be careful! There can be live voltage at the valve even when it is not working, when the machine is simply powered on. 

 

[WestTn]

18 hours ago, HockeyGuy said:

vee8power and WestTn,

I am not able to view vee8power's image, I am seeing the following instead:

"Sorry, we can't show this content because you do not have permission to see it".

I am also not able to post images of my own.

I am however able to view the image posted by WestTn.

 

Look for the tech sheet it's generally attached to the lower skirt of the dishwasher. You'll find the wiring diagram which you certainly need, you'll also find the resistance specs of each load ( example : wter valve 1200 ohms) 

Check all loads in the wtr valve circuit as the control board will stop supplying 120v to a load if it senses problems afoot.

[HockeyGuy]

vee8power - ok, thank you! yes, I am very careful but thank you for the additional warning.

WestTn - I will find the tech sheet and will follow-up accordingly on your recommendation.

These pointers are very much appreciated! 

Regards,

HockeyGuy