How to Troubleshoot & Replace Ge AP7218675 / WD21X31900C Configured Mc Board

I first tried changing the door latch, that didn't solve the issue and I realized that it was a software issue and the control board was not functioning properly. Changing the control board was surprisingly easy, I followed the instructions in this video: https://www.youtube.com/watch?v=SnlGOBVZt1U&ab_channel=Drewin%27Around After unscrewing/rescrewing a few nuts and unplugging and replugging a few connections - the dishwasher worked! 

I replaced the latch and the control board. It was very easy, both things together took about one hour! Much cheaper and easier than replacing the whole dishwasher.!!!!!!!!! 

Bought the door latch and control board. Replaced the door latch first within 15 minutes and it did not solve the problem. Replaced the control board and set the jumpers as per the enclosed instructions and the dishwasher still would not run. I viewed the old control board without jumpers and then set the new control board back to the way it arrived (not jumping out). Reinstalled the control board and the unit ran perfectly. The instructions that came with the control board are misleading. 

1st, I replaced the door switch. Didn't fix it. 2nd I ordered the control board and that did it! What impressed me was the quick delivery of the part! I look forward to using your site for future repairs. 

Purchased GE Service Machine Control Part# AP6974044 (WD21X24902) and GE Door Latch, Part# AP5668411 (WD21X10490) with the expectation that one or both parts are bad. Upon completing multiple hours of online video training, courtesy of the Internet, I chartered into unknown waters. First item was setting the "personality" of the replacement board. The included paperwork indicates what setting is required; however, it doesn't mention how to complete this step. There is a plastic housing that pulls up for each of the four terminals, similar to a Lego piece. Problem #1 solved. Next item was wrestling the board back into its proper location without gutting the dishwasher innards in a fit of rage. Patience is required, young grasshopper! Final item is clearing the dishwasher from service/diagnostic mode: documents show only five (5) LED blinks in the legend while in service mode. Despite pressing the Cycle Select and Power button, I was unable to exit the mode so I figured I was out of $100 bucks and time to purchase a new dishwasher, but why is my dishwasher blinking six times? I finally selected that option and VOILA! My dishwasher works once again! 

Used the forums to diagnose the issue by accessing the control board and looking for blink codes. There were absolutely no lights on the board while the interface board/display lights were lit so I deduced the control board was bad. After receiving the board, I followed the instructions to set the jumpers for my specific model, pulled the power from the unit, replaced the board, and plugged everything back in. I started a cycle, closed the dishwasher door, and everything worked. Nut drivers made everything easy, and I would recommend being especially careful pulling the connectors off the old board. There isn't a lot of room to work and if you pull the wires out of one of the connectors or crack a connector, you won't be very happy. 

Replaced control board and door switch. 

I replaced the service control board. 

Replaced main circuit board. 

Dishwasher model PDF820SGJ0BB would not start, made sound as if door had just been opened mid-cycle. Power cycling it used to reset this behavior (tech told us it was just caused by RF interference). Finally it wouldn't reset and always gave that sound, would not run. Found info on how to enter front panel user service mode (hold Select Cycle and Start buttons down together for 5 seconds, until chime, then release) and it had all lights are flashing, showing it was reading the door as open, even when it was closed. Gave 180 code when it stopped flashing. (exit the diagnostic mode by holding Select Cycle and Start together again until the mode clears, about 3-5 seconds). Everyone (and I mean everyone) I found talking about it online says to purchase a new Controller Board. For this model, it's WD21X31900 (AP7208393). A lot of people also say to get the door latch just in case (it's under $30, why not?). I bought both, but the controller board did the trick on its own. Takes about an hour to replace, very fiddly work where you'll wish you had an extra elbow and smaller hands, but nothing really complicated. A nut driver/hex extension or flex driver is very helpful.