Bosch dishwasher problem

[olneycc]

I have a 9 yr old exxcel dishwasher sgs4442. recently it has been giving poor wash results so i guessed it was time to clean out the water filler matrix again, I've done it twice before with good results. This time i noticed there was water in the base and i could see the flood switch was not being operated because the plastic housing for the float was full of crud.
I cleaned it all out as usual and this time cleaned out the water transfer hose at the front which was almost completely blocked. I drained the base by laying the machine on it's back.
The problem I now have is that the machine will not take in water after it has completed the prewash. It starts by filling then shuts off the water and pumps very strongly. It then drains the water, opens the dispenser draw and starts what sounds like a suction pump but no water is taken in. The machine will just stay in this state continuously. I can reset the machine and get the same results again. I checked with a multimeter that 240 volts is switching the solenoid valve to let water in at the initial fill but there is no reading when its time to refill after the first drain.
Could it be a control module problem? Any ideas what I should do next?

 

[zipper]

Sounds like you have a leak & it has tripped the anti-flood device. Lean the dishwasher forward to drain any water off the base-plate (have old towels handy), then remove the side plates & cover under the door. Run a cycle & observe for leaks.

 

[olneycc]

It was leaking from the pressure chamber on the left before I cleared it all out. That all works ok now. I drained the water from the base as well. When you say anti flood device do you mean the float in the base that trips the pump to empty the machine? Is there any other device that needs drying out? Why does it fill ok and do the pre wash and then not refill for the rest of the cycle?

 

[zipper]

Yes...the polystyrene disk is part of the anti-flood device. If you have a leak then water accumulating on the base-plate will eventually raise the float & activate the drain pump (how quickly this happens depends on how bad the leak is). As long as water remains on the base-plate the drain pump will run & no water will enter the machine. You may have bad seals on the wash motor...you may have a leak someplace else. What you need to do is remove the side plates & look for a source.

 

[olneycc]

thanks but cleaning out the transfer pipe cured any leaks, I drained the water from the base and it works ok now except it won't take any water in for the second fill. It does the prewash then empties out and doesn't take water in again.
Any ideas?

 

[far0n]

If you take the left side panel off you'll be able to see the anti-flood device.... that red/yellow contraption. In the anti-flood device there's the yellow half which looks to be some sort of water level pressure sensor. If you take the whole anti-flood device apart, strip out both the yellow and red parts, then dismantle the yellow disc shape, you'll see a silicone bladder inside with a tiny plastic insert that lets air in to inflate it. You may need to clean this out. When the bladder inflates it flicks the microswitch to start your cycle. If the bladder doesn't inflate it'll keep pouring water in until eventually the anti-flood kicks in instead. Put it all back together and hey presto... when the water flows in, you'll eventually see the bladder inflate, the blue arm rotate and cycle start. It may not be this causing your problems but it's worth a crack.

 

[olneycc]

Well I took that yellow diaphragm housing apart and it was completely clean but when I put it back together guess what?
Your right, 'Hey presto' the machine works perfectly. Now I'm not sure if it was that that did it or the fact that the micro switch terminals were a bit corroded but you pointed me in the right direction so many thanks