Bosh SGV43E03 Dishwasher not running wash cycle

[encodeme]

Hi,
We have the above dishwasher and its not going through its cycle.

On starting it begins to run water into the matrix. Then the flow stops and the pump comes on for a few seconds, stops for a few seconds and repeats, but nothing further happens.

If I cancel the cycle by pressing all 3 wash setting buttons.... The machine goes into the empty mode, expels the water and sounds the end of program alarm.

I've had the control board out, and all looks fine with no obvious burnt or unsoldered items.

I'm not sure what the next step would be?

 

[Leccy758]

Not sure if this machine has a flow meter or a pressure switch to measure water entry.

If it has a flow meter (round disc with inlet and outlet pipe fitted and a lead with two wires on near the fill valve under at the rear left of the machine) a symptom of the reed switch failing is the appliance fills for a few seconds then stops, emptys, possibly trys to fill again empties and stops on some or just continues the fill drain fill cycle on others.

The reason it fills then stops and empties is that the PCB is not getting the correct pulse signal back in the time specified.

 

[encodeme]

If it has a flow meter (round disc with inlet and outlet pipe fitted and a lead with two wires on near the fill valve under at the rear left of the machine) a symptom of the reed switch failing is the appliance fills for a few seconds then stops, emptys, possibly trys to fill again empties and stops on some or just continues the fill drain fill cycle on others.

The reason it fills then stops and empties is that the PCB is not getting the correct pulse signal back in the time specified.

Hi, you were absolutely right... this model has a flow meter with a reed switch.
I've had the reed switch out and activated it with a magnet... it appears to be working ok.
Whilst down there I removed another switch which is "plugged" directly into the matrix bottom frame. This has a yellow & rubber end on it and I suspect is opened by water flow?
It certainly was not stuck, but also showed an open circuit on ohms?
Its a kind of switch I've not dealt with before
Once more I'm somewhat out of ideas.
Is there a diagnostic sequence to play on the selector buttons?

 

[Leccy758]

how strong a magnet did you use to activate it (the one on the unit is quite weak), we have a test rig we built to simulate the reed switch operating using a relay and a seperate supply.

Another way to test the reed switch is to gently blow in the flow meter and check with an ohmeter for a make and break contact. Did one on friday that although it closed it had a small resistance (the magnet had twisted the reed) so we replaced the reed switch with a new one from RS (about 50p) and all was ok.

 

[encodeme]

Again I think you are right. When I blow through the unit the reed switch doesn't open, it stays in the closed position.
My next task then is to track down a new reed switch... I'm currently in Portugal.... Its not as easy to find things as in the UK.
I'll keep you posted... Once again many thanks
PS do I need a N/c or N/o, Ive noticed 2 types on sale at Maplin... not sure which would be best
http://www.maplin.co.uk/Search.aspx?criteria=reed switch&source=15

 

[encodeme]

I fitted the reed switch and now its working fine.
many thanks