I've replaced the pump/motor, piston valve, air gap, and disposal,
checked all drain hoses, and checked both the drain solenoid switch and
the float switch.
When I simply put the main drain hose into a bucket (to test operation)
the D/W works perfectly. It moves from cycle to cycle with no
indications of problems. The drain solenoid releases at just the right
When I connect the drain hose to the air gap/ disposal, the D/W still
visually drains completely (in a very short period of time) but the
BLOCKED DRAIN light comes on about 1 minute after the water visibly
stops draining into the sink/disposal. In this mode I can see that the
drain solenoid is still powered and does not release the drain solenoid
switch. I can reset the D/W by disconnecting power and starting over
but the same thing happens at the end of the first drain cycle.
My sense is that this could be a timer problem but why do things work
perfectly when the drain line goes into a bucket. It almost appears
that 'something' senses the additional 'back pressure' caused by the
airgap and disposal. I am 100% sure the air gap and disposal are ok
(the disposal knock out plug is out and is not the issue).
What else could cause this problem? Thanks for any help you could