Testing turbidity sensor ( the OWI ) in a Dishwasher

[BrokenDW]

Hello,

I have a question on how to test a turbidity sensor in a DW. From the web I have read this:

" you can test the turbidity sensor at connection P12 of the control board. From pin 1 to pin 3, "

Also I have included the actual board as an image. 

I have 3 questions on this. Assume the power to the DW is OFF.

1. Do you touch the probes which are yellow lines and referenced as A in the image?

2. Do you touch the probes which are orange lines and referenced as B in the image?

3. Why can't you take out the OWI sensor completely from the DW, and test pins 1 and pins 3 on the actual OWI sensor?

I have not mentioned Ohms here at all, since the problem is what exactly do the multimeter probes come in contact with.

 

Thanks,

Rick

P.S. In advance I hope I posted this message to the correct section of this forum.

 

[BrokenDW]

I apologize I uploaded the wrong image. But instead of figuring where on the control board to touch the probes from a multimeter, can I simply remove the OWI sensor and test for the relevant pins on the actual OWI sensor?

 

Thanks,

Rick

[Terry Carmen]

The sensor works by measuring light transmission through he water. The only useful way to test it in the home is with the diagnostic procedure in the tech sheet, which actually runs the sensor and checks the output.

A meter can tell you if it's open or shorted, but can't tell you if it's actually working.

 

Edited January 5, 2022 by Terry Carmen

[BrokenDW]

Terry thank-you very much on this. I think you are saying is if it is Open then replace it. But if it is not open then without additional testing you cannot fully determine if the light feature is working?

Thanks,

Rick

 

[Terry Carmen]

2 minutes ago, BrokenDW said:

Terry thank-you very much on this. I think you are saying is if it is Open then replace it. But if it is not open then without additional testing you cannot fully determine if the lightfeatur

 

Yes, if the sensor is actually open or shorted it's bad.

If it's not open or shorted it still might be bad.

The only reliable test is the one that you do from the control panel in test mode.

The way the sensor works is by shining a light across a gap onto a light sensor.

The test from the control panel, at least on Whirlpool, actually checks the sensor when there's water present and no water present and can tell if it's bad.

Edited January 5, 2022 by Terry Carmen

[BrokenDW]

Terry thanks for the additional info. I can say I do not have the skills needed to do the complete test. But do understand now there is a lot more involved than merely measuring Ohms. 

I think for 10 to 15 bucks I should just get a new OWI, just to be sure. And this is my own DW too.

Rick

 

 

 

[Terry Carmen]

It's great to work on your own dishwasher! Anytime anything even looks like it's a little bit off go ahead and take it apart and fix it. Just consider it the cost of training.

I did that on my GE dishwasher I think I've replaced everything out of at least once, but for the cost of a few parts I'm really pretty good at GE dishwashers now.

Anytime you can get really solid training for a couple hundred dollars in parts it's a good deal.

[BrokenDW]

Terry I agree with you 100%. To often people say how old is it again? And if you answer 6 years ( u see 5 years is OK )they say time to replace it. They don't even think why they even say that.

But if the tub is not broken, and nothing is rusted I say keep it and figure out what usually ends up to be a minor problem.

Even something as expensive as a control board, I found a refurbished one for about $90.00 several years ago. It is still fine and the original one was burnt.

My dishwasher is about 14 years old and brand new it was about 700.00 I think. So since then I have spent about 250.00 for parts to fix the one I have. And have learned a lot like you said.

Thanks again,

Rick