Electrolux dishwasher pcb repair

[zio_mangrovia]

Model 911939224-01
TT50e

When I power on my dishwasher, water is never loaded and drain pump starts immediately and never stop itself even if empty state occurs.
There is no anti-flooding system although service manual shows it but paper lists several models.
I checked directly the two pressure switch (both level and overflow) blowing in tubes, tester showed zero resistance and immediately after blow infinite resistance.
I wanted to check wiring for only level pressure switch disconnecting it from pcb, I used tester to check signal to connector with both water and no water. This worked fine.
I checked door switch was closed.
I think problem is in PCB, I call technician and He confirmed it
Then I try to desolder only the gate pin on acs108-6s (overvoltage protected AC switch, which is the triac which drives drain pump) and when I power on dishwasher, pump doesn't start.
I think if problem was about drain pump driver circuit, dishwasher should have to load water and this one never occurred.
What can you suggest me now please?

 

[Alec_t]

It seems the machine thinks there is water above the pump-out level even when there isn't. A possible cause (other than a faulty circuit board) could be a faulty pressure switch or clogged tube leading to the switch. Blowing into the tube may exert a greater pressure than the the water would normally provide, so may not be a reliable test. Also, blowing may have only temporarily dislodged slime/sediment normally obstructing the tube.

 

[zio_mangrovia]

It seems the machine thinks there is water above the pump-out level even when there isn't. A possible cause (other than a faulty circuit board) could be a faulty pressure switch or clogged tube leading to the switch. Blowing into the tube may exert a greater pressure than the the water would normally provide, so may not be a reliable test. Also, blowing may have only temporarily dislodged slime/sediment normally obstructing the tube.

I verified, by manual service, there is infinite resistence (in empty state) in connector which references overflow pressure switch and this is the right value.

 

[Maxwell]

If you disconnect the power from the drain pump, the dishwasher will not start the program, it will just sit there.

considering you unsoldered the gate, that's exactly what is happening. It seems the pump circuit is getting the signal to pump when it shouldn't, could be a short in a smaller switch controlling the gate.