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FIXED GDF645SGN0WW - GE Dishwasher fills (and drains). Circulation Pump doesn't commence

SJCN

Premium Member
Joined
Dec 30, 2021
Messages
5
Location
Seattle
Model Number
GDF645SGN0WW
Brand
GE
Age
1-5 years
Situation : Dishwasher starts. Sump pump drains standing water and refills. The timer counts through the full cycle. However there is no action with the circulation pump/wash arms. It doesn't begin. Dishes are not sprayed nor cleaned.

Previous Activity (and questions)
1. UI - I recently replaced the UI board in the door (no lights on the unit). Is there a PERSONALITY JUMPER SETTING that I have to set for this particular unit? If the Jumper Setting was incorrect, would this prevent the circulation pump from activating?
2. CEM - I did Consumer Error Mode (START/SELECT held down for 5 seconds). Lights go on. Hold, then turn off. How do I launch into the Consumer Service Mode to test if the circulation pump works?
3. Circulation Pump Test - I removed the circulation pump and tested with a direct power source. It works, with the Impeller rotating freely.
4. Tech Manual - I have a TECH MANUAL for units (GDF650SxJ0xx/GDT655SxJ0xx). Does this cover my model, or is there another that is more model specific?
5. Float - I have been told that a float could be stuck. Does this model have such a float that could prevent circulation pump from starting?
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
134,109
Location
Redmond, Oregon
1. I'm not sure if this one comes with jumpers or not, this is one I've not seen before:
If it comes with instructions and jumpers, then the jumpers must be set per the instructions.

2. Here's the service manual: https://drive.google.com/file/d/15CmFe-hcufL5XUJPsqlEN3AzwDZ6z0M-/view?usp=sharing
Page 47 tells you how to enter Service Mode. NOTE: The dishwasher must be in Consumer Error Mode to enter Service Mode, Look on Page 45 to enter Consumer Error Mode first.
LED blink# 3 is circulation pump, see if the circulation pump runs.

If the circulation pump runs then its fine.

Remove the pressure sensor and see if something is semi-clogging it.

Here's the pressure sensor for your model:

Watch this video to access it:


Let us know how it goes.

Jake
 

SJCN

Premium Member
Joined
Dec 30, 2021
Messages
5
Location
Seattle
Thank you very much, Jake, for the thorough reply, as well as the ideas on the pressure sensor. It was heavily used by the tenant, so good chance there could be junk in there. That youtube link is helpful.

I need to look at the ultra-fine filter, too, as I've read elsewhere that could prevent water flow to the impeller.

I was also told that a stuck 'float' could be a cause for holding things up, but couldn't find where one might be.

I will check after the holidays. Sending that technical manual is fantastic and much appreciated.

Regards, Simon
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
134,109
Location
Redmond, Oregon

SJCN

Premium Member
Joined
Dec 30, 2021
Messages
5
Location
Seattle
Hi, Jake. Thank you for your patience, while I postponed getting back to looking at the dishwasher until this weekend............

I removed the pressure sensor. There was nothing semi-blocking it, but it did seem that the internal diaphragm was stuck. I was able to loosen it up (so it seemed) by physically . I couldn't figure out, though, how to test it with my multimeter, Does it typically fail electronically?

I ran the dishwasher through the SERVICE MODE. At test point with #3 (Circulation pump), nothing was happening. Previously I tested the circulation pump while it was out of the dishwasher (using a power code/alligator clips), and the pump ran. Today, with the pump back in the dishwasher, running the SERVICE MODE, it didn't launch.

1. Is a failed pressure sensor enough to prevent the circulation pump starting - even when the machine has been primed full of water?
2. Is the harness a typical failure point that could prevent the circulation pump from working while in the dishwasher (even though it worked stand-alone on the workbench)? The sump pump is working with no issue.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
134,109
Location
Redmond, Oregon
1. Is a failed pressure sensor enough to prevent the circulation pump starting - even when the machine has been primed full of water?
2. Is the harness a typical failure point that could prevent the circulation pump from working while in the dishwasher (even though it worked stand-alone on the workbench)? The sump pump is working with no issue.
Use the flow chart to find the culprit: Page 56 here: https://drive.google.com/file/d/15CmFe-hcufL5XUJPsqlEN3AzwDZ6z0M-/view?usp=sharing

Page 51--->Testing the Pressure Sensor.

Jake
 

SJCN

Premium Member
Joined
Dec 30, 2021
Messages
5
Location
Seattle
Thank you, again, Jake, for your patience as I got to the unit on/off.....

In running through the SERVICE MODE, #3 (circulation pump), continues to be a 'no go'. Testing for power leaving the main board, it seems that there is no power going out to the pump. The pump works when tested independently of the unit (straight to a 120V line, but there is no action when it is plugged in through the board (or tested on SERVICE MODE).

Does that pressure sensor control power going out to the circulation pump - in other words, if the pressure sensor is malfunctioning, does it somehow prevent power (at the board) going out to the pump? (We have tested the sensor, and it doesn't seem bad - it does work to fill/empty water). It fills up to the right level. The water heats, the timer counts down, eventually the dishwater drains... Just at the point the circulation pump should start, there is no movement.

Testing for power at the board, there seems to be no power at the 'plug' going out to the circulation pump. (irrespective of the pressure sensor). Would the circuit board be malfunctioning just at the circulation pump power source?

I really have appreciated your feedback. I've found nowhere else on line as insightful and as useful.. Thank you.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
134,109
Location
Redmond, Oregon
Ok, in the service manual look on Page 56, if no power is coming out of the board it says--->Is the machine control board fuse open? Ohm test it for continuity. Disconnect power to the dishwasher first.

(click to enlarge)
Screenshot 2022-07-29 07.37.38.png

Here's the machine control board fuse for your model:

If the fuse is good, it says to replace the machine control board.

Here's the machine control board for your model:

Jake
 

SJCN

Premium Member
Joined
Dec 30, 2021
Messages
5
Location
Seattle
Hi, Jake.

BINGO! Thank you for your help walking me through the task.... GREAT information and guidance, and very much appreciated.......

The fuse was tested and was indicating GOOD. As you directed, the remaining machine control board was the culprit. We got ourselves a new one, and ...........

SPINNING WASH ARMS and CIRCULATION PUMP!

and clean dishes.............!!!

Again, thank you very much. You are a Wizard.......
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
134,109
Location
Redmond, Oregon
Excellent, glad to hear the new machine control board fixed it.(y)

Thanks for the update!

Jake
 
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