Brand: LG Model Number: LDS5540ST Main Symptom: Does not fill with sufficient water What happens & when:
It seems like the dishwasher does not fill with enough water. After the cycle, the dishes are often greasy or otherwise still dirty, and there is undissolved detergent in the detergent tray. If I add water to the dishwasher during spray cycles, the machine works well - all the dishes are clean and there is no undissolved detergent. Please ask any questions to help diagnose the issue. If I open the dishwasher during a spray cycle without adding water, there is little water in the bottom of the tub and not much coming out of the spray arms in the second or two after I open the door.
I watched the float assembly while the machine was trying to fill - water was flowing in. The floats are clean and move freely.
In the photo I’m trying to test water inlet valve solenoid resistance but not sure what I should be seeing.
Thank you for any help! I can post a video of the float assembly during fill if that would help.
Since water comes through, the coils of the valve would not necessarily be an issue. However, this does not eliminate the valve since there are mechanical internal parts that can’t be tested with a meter. When the dishwasher initially fills, how long does it fill for before it starts a wash cycle?
During the initial fill on the Normal cycle, which is for a pre-rinse:
Fills for about 1 minute 15 seconds (the float that can go highest before tripping a switch goes all the way to the top of its chamber and trips its switch).
Then there’s some activity (pumping and maybe draining?), then another fill for only 15 seconds.
It sounds like the dishwasher is skipping around in the cycle. It should start with a drain, stop and then fill, then start a circulation cycle. As it sounds like the cycle process is skipping around, the main control would be the likely cause of failure. EBR73739203 Main Control Board | Genuine Lg OEM In Stock
Based on the video, the dishwasher does not stop filling when the drain kicks on. This is going to indicate an overfill failure. The switch with the yellow wire should have had continuity when the float started to raise up and activate the switch. When the water is filled enough for the float under the number 2 switch to raise (can fill the dishwasher up with 1/2 gallon of water while the power supply is turned off), does the switch have continuity when the float activates it?
I apologize, the wires would show continuity based on the wire placement in the picture. The wiring diagram shows it as an open circuit. When the float is pushed up, does the switch drop continuity on those terminals? The water is not supposed to fill enough to activate the switch on the left which is what is causing the drain pump to kick on.
Based on this, it sounds like the main control is continuously sending voltage to the inlet valve and causing it to over fill the tub. This is resulting in the drain pump operating to prevent a water leak. As the switches are working properly, the main control would be the cause of failure.
