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Tyler Z.
Tyler Z., Appliance Doc
Category: Appliance
Satisfied Customers: 81886
Experience:  9+ years being an appliance technician with factory training.
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Kenmore clothes dryer won't start has error code F 40

Customer Question

Kenmore clothes dryer won't start has error code F 40
Submitted: 2 years ago.
Category: Appliance
Expert:  Tyler Z. replied 2 years ago.
Hello, and thank you for using this service. I'll be helping you with your problem today.F40 is a communication error between the motor control board and the main interface control board. The big problem is that you don't know which control board is causing the issue and there is no way to test, so it's a guessing game. You can definitely take the dryer apart and make sure the wire connections are secure--but if everything checks good, a guess will need to be made and one of the control boards replaced. Usually the motor control board is the part that needs to be replaced but there is no way to know 100% for certain so it's a bit of a gamble that even we as technicians must make. Either way, below is a link to the control board you'd need to order for your model. CLICK HERE for motor control board We are on the honor system here. Please remember to rate my service before you leave today. If you need anything else, just let me know. You can continue asking follow-up questions at no additional charge after rating my service if you still need assistance.
Customer: replied 2 years ago.

It would seem there should be some way of testing the inputs to the board to determine whether the board is bad or it has a faulty input.

Expert:  Tyler Z. replied 2 years ago.
There actually is not. The signals sent to the board and back are not sustained signals, they are burst signals and they are square waves so you can't actually test this with a normal meter. You'd have to have an oscilloscope and lab equipment.
Expert:  Tyler Z. replied 2 years ago.
Hello again. I'm just following up because I haven't heard back from you and I see this question is still open. Is there anything else I can help you with?