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WDTA50SAKZ0 - Whirlpool dishwasher wash motor won't spin, gets hot

freqsounds

Premium Member
Joined
Nov 13, 2022
Messages
2
Location
US
Model Number
WDTA50SAKZ0
Brand
Whirlpool
Age
1-5 years

About the machine:

Brand: Whirlpool
Model: WDTA50SAKZ0
Warranty: Expired 4 months ago

I bought and installed the dishwasher (brand new) about a year and 4 months ago. Up until 3 weeks ago, I did not have any problems with it what-so-ever. One afternoon, I went to unload the dishwasher to discover the dishes were still dirty. At first, I thought maybe it hadn't been started; however, the soap dispenser had opened and leaked down the door. The soap was still concentrated, so I don't think it sprayed water at all during that cycle.

I restarted the dishwasher and stayed within earshot. I heard the drain pump kick on, but nothing sounded unusual. After the drain cycle, it began filling with water. When it was about half full, I could hear the wash pump start to buzz. The buzzing ramped up quickly and stopped with the sound of a switch clicking off. The sound seemed to have come from underneath the unit. I immediately hit Cancel and it drained and shut down. I secured the power and water, then pulled the unit from under the countertop.

I could tell something was wrong right away. I went around to each motor to make sure the plugs were seated correctly, starting with the wash motor. There was an odd smell coming from the unit. It reminded me of the smell of a hospital. I reached for the plug and discovered that was a bad idea. The wash motor was incredibly hot. I pulled my hand back before touching the motor. It seemed like it was hot enough to cause burns if I had touched it.

I gave the wash motor time to cool and decided to remove the pump to check the range of movement. Much to my surprise, the impeller moved freely. I pulled the service manual to check the specs, which described resistance between 7 - 15 ohms. I confirmed it was within spec, reading at 9.98 ohms. I put it all back together and checked the connectors underneath and made sure the connector's contacts were tightly gripping the contacts on the wash motor, then I leveled the unit and entered diagnostics mode.

I checked for codes by pressing the 3rd key while in diagnostics mode. There was only 1 code: F7 E1 I looked it up in the service manual... wash motor failure. I cleared the code and tried to run a cycle. It started off draining for about 45 seconds, then began filling with water. I heard the wash pump turn on, but it wasn't buzzing like I heard before. About half way through filling, it did it again -- a buzz that started light and ramped up before clicking and shutting off. I let the dishwasher continue its cycle anyway. When it was complete, I secured power and water again. Same as before, the motor was much hotter than it should be, and the hospital smell came back. At this point, I'm assuming the weird smell is the burning of the resin on the transformer wire.

Initial thoughts pointed to the motor not getting enough power. I metered the wires at the motor while running diagnostics. When the cycle first began, it read 125V. I could tell the motor was getting voltage through the vibrations in the test leads, but it didn't seem like it was spinning. I waited for the signature buzzing noise. During the buzzing noise, the voltage dropped to 123V until thermal protection enabled, then it went back up to 125V, but the motor was definitely off. I checked all the other motors and the heater, all of which returned good voltage and resistance values as described in the service manual.

I picked up a "new, open box" motor on eBay. It arrived a couple days later. Before introducing to my dishwasher, I did a resistance test (9.06 ohms) and made sure the impeller spun by hand. It required about the same effort to turn as the original. I installed it, ran a cycle, and same thing -- it got hot, smelled like a hospital, and ultimately did not spray any water. Out of curiosity, I grabbed a meat thermometer, and the motor casing got up to 323ºF!

By this point, I'm thinking maybe the housing is interfering with the impeller's motion (i.e. maybe the plastic warped or something). I went online and decided to order the entire sump, brand new this time. I installed it when it arrived a couple days later, and the exact same symptoms.

It doesn't seem likely that 3 motors have the exact same issue. I found some forums that describe similar issues, but replacing the wash motor fixed the issue for many people. I moved on to other areas, like checking the wiring throughout the machine, checking the connectors and contacts, and performing a continuity test on the wiring itself in case there's additional resistance somewhere. I came back with nothing.

I took the control board out, took a look around and tested some of the components on the board. The service manual mentions checking the triacs, indicating that the triacs control a majority of the high voltage components, so if one thing is working (i.e. the drain motor), then the triacs should be OK. It also described the two fuses, one inline with the neutral, the other inline with the live. I performed the test of checking continuity between P5-1 and P5-4, and they tested OK. I checked the fuses individually, they tested OK. The only things that tested under spec were the two electrolytic capacitors on the board; however, they were definitely within 5% of their labeled values. After tracing the circuit, I don't think these caps influence the wash motor circuit. I also tested the relays on the board by desoldering and checking continuity of the pins while triggering with 12VDC on a bench. Everything looks good on the board.

With everything testing OK, I took one of the 3 motors and connected a test cable to the contacts on the motor, put it in a vice, and powered it up just for a couple seconds. It made noise, but it didn't spin. The impeller just jittered back and forth as if it didn't have enough power to start. It also began warming up just like it does in the machine. I didn't keep it on long enough to tell whether it would get as hot or if it would trip thermal protection, but I think if I kept it on long enough, it would probably reach that point.

At this point, I'm out of ideas. I am thinking there's something wrong with the electric service in the house, but all the tests I've run appear OK. The outlets are at 125VAC, 59.9Hz, tested multiple circuits in the breaker box (kitchen (20A), garage (20A), and dishwasher (15A) breakers).

I've tossed the idea of buying a new control board, but decided not to since I can't get the motors to start when directly hooked up to the mains. It seems like a power issue, but the voltage seems OK, resistance values check OK, connections are tight. Am I overlooking something? I find it unlikely that 3 motors are bad.

Bonus question: Although this motor only has 1 coil, would a 'run capacitor' be of any benefit here?
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
136,041
Location
Vicksburg Junction, Arizona
I'm attaching your tech. data sheet below. P5 Pin 1 and Pin 2 is the wash motor assembly pins that send 120 volts to the wash motor. If you get 120 volts AC there and at the wash motor, the problem is the ebay wash motor. We never recommend parts from amazon or ebay. We only recommend OEM parts.

In-stock--->OEM pump(wash motor) assembly: Base-Pump W11460963

OEM motor and sump assembly: Pump&motor W11460945
 

Attachments

  • tech-sheet-w11366143-revb.pdf
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Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
136,041
Location
Vicksburg Junction, Arizona

freqsounds

Premium Member
Joined
Nov 13, 2022
Messages
2
Location
US
the problem is the ebay wash motor.
The eBay wash motor is not currently installed. I ended up ordering the entire sump brand new from Whirlpool (the same part number you listed for the motor and sump assembly above). I had the same issue with the new sump. I submitted a warranty claim to Whirlpool, and they sent a 2nd sump (new), and I'm still seeing the same results.

So the original pump, the eBay pump, and two new sumps with pumps preinstalled are seeing the same problems. I know, I know... "It's probably not the pumps..." I agree, although I leave a little room for plausibility. The wiring, connectors, and control board have been tested using a Fluke 289, and process of elimination by replacement and/or bypassing.

The major concern with this problem is when the pump is removed from the unit and put in a vice with the mains directly connected to it, it still doesn't rotate as you'd expect. It 'shudders' back and forth, but rarely starts turning full revolutions (if you keep trying, you *might* get it to spin, but it's a coin-flip). This occurs with all 4 motors.

I had an electrician come out today. He said everything is okay in the house, 125VAC @ 60Hz are the results. We tried (again) putting the dishwasher on 3 different, segregated circuits (locations: where the unit is permanently installed on its own breaker, plugging in an outlet in the kitchen (GFCI), and in the garage) with the same results. He unofficially recommended the next step is to yeet it into the front yard, and find a different one. :LOL::ROFLMAO: All joking aside, he said the AC service checks OK and there is no reason (as far as electricity is concerned) for the motor to not be working as designed.

I'm attaching your tech. data sheet below. P5 Pin 1 and Pin 2 is the wash motor assembly pins that send 120 volts to the wash motor.

This is the same service manual I was using during troubleshooting. The results of testing P5-1 and P5-2 is ~123VAC when the pump is trying to start. When thermal protection engages, it jumps back up to 125VAC.

The fuses and Triacs were tested on the control board. I also tested the capacitors by removing them and testing with an EGR meter. They're within spec. The control board itself seems to be functioning properly. There's voltage when there should be, and no voltage when there shouldn't be. The touch control panel works as it should; we've never had any problems selecting a cycle or entering diagnostics mode. Up until 4 weeks ago, we hadn't had any issues with it at all.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
136,041
Location
Vicksburg Junction, Arizona
Then you have a very odd issue I can't help you with just on the forum here, I would need to come to your house and see what's going on.

>ITS BEST You contact Whirlpool at 1-866-698-2538 and have a tech come out, the tech can call the factory on a special FACTORY HOTLINE tech number from your house, and the factory can get involved in investigating
 
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