Dishwashers can be a pain to diagnose correctly. A recent example is a Samsung DMT400 RHS that gave me a fit with the delicate blinking light corresponding to a drain problem. Used the fast tract for diagnostics.
Reset control board (Unplug/Replug unit), put into diagnostics & went thru cycles with drain cycle toward end of service mode. Unit drained but flow was weak, so I inspected disposal inlet & drain hose for blockage which was first problem to inspect on Fast Tract. No restrictions found, next on list was drain pump.
The ohms found on the pump were below specifications so I suspected pump was weak & shaft possibly seizing. Replaced pump, flow was improved, but the flow still seemed weak. Dishwasher worked for a few loads then shut down again with the delicate led blinking. Posted question what am I missing & got feed back of blocked drain hose and case sensor which is next on list of problems.
Replaced case sensor on this unit over a year ago for filling issue, did not think that it was the culprit although there was sediment building in the assembly.
I replaced the water sensing case assembly as a parts changer not knowing how much millivolts to check for at the board. Also rechecked drain hose & blew thru drain hose from case brake back thru pump & into tub. No restrictions felt there, could hear the tub water gurgling. Reinstalled machine & babysitted cycle (watching paint dry) completed wash cycle & drained with what I perceived as weak flow, but drain it did with no problem. Two days later another call for incomplete cycle. What is going on? Bad PCB board which was last thing in problem list.
Now I am really determined, set aside 3 hours to focus completely on the machine. One thing I did not do was check harness connections so that was in the battle plan. Arrived reset board, started normal cycle, pump did initial drain with very little water in sump, filled, & washed ((watching paint dry again but I viewed posts on Appliantology in the process).
Finally began drain cycle. With hose in bucket the flow was sputtering Knew for sure I had a blockage problem. I pulled main drain hose off took it outside & run high pressure garden hose water, passed with flying colors. Next I pulled hose from pump to case brake, applied water pressure & that is when the culprit was dislodged. What appeared to be a couple of small feet that are attached to some cutting boards.
Now apparent the intermittent problem was these feet caught in the bend of the drain hose that would pivot allowing water to flow at a reduced rate & then turn enough to plug the gap allowing very little flow thus causing the drain cycle to time out before completely emptying the sump.
Moral of this story if having a intermittent drainage problem that shuts down a dishwasher, Samsung in particular, eliminate all drain hoses as a possibility of blockage by putting high pressure(60+ psi) water thru them with an outside garden hose.Link to
forum topic: http://appliantology...r-dmt400rhsxaa/