Bosch Dishwasher problem model sgs43A12GB

[beweek]

Hi,
I am hoping someone can help me with a problem with this Bosch dishwasher. The main symptom is that it is not washing properly and I have found out that sometimes the top arm appears to work normally and then the bottom arm. When I last looked both arms were gently spraying water but neither was turning, when only one arm was working the arm was turning. Both arms turn easily and the water pressure/volume appears low. I have checked the pump, arms and pipes for blockages and all appear clear as do the filters. The water level looks right and the timer runs normally and the machine makes all the noises of normal washing
As there is a separate feed from the bottom of the "tank" to each of the arms, do the arms run in turn or should they both run together. If so is there a valve to control this.
All help and advice gratefully received
Thanks Bernard

 

[Leccy758]

First thing to check now is the nozzles on the spray arms as they are prone to getting blocked

 

[zipper]

Follow the good advice Leccy gave you.
Regarding your question about the spray arms rotating in unison: On a wash cycle the lower spray arm rotates for 60 secs...then the upper spray arm rotates for 55 secs (changeover takes 5 secs). Both arms do not rotate at the same time. This process is controlled by a geared synchronous motor, cam plate, micro switch & slide (not a valve).

 

[beweek]

Thanks to Leccy758 and Zipper for the fast reply and great information. The spray arms are clear and as both arms are continually spraying water at the same time my guess would be the motor and cam plate assembly is the problem. I realise to gain access I will need to lift the tank away from the motor assembly, I can see some of the screws on the side and back and presume I will also need to free the sump bowl and the salt dispenser. Is there anything else I should look out for?

Thanks again
Bernard

 

[zipper]

Bosch call this system "water points" goodness knows why...
The synchronous motor that drives the gears ( & therefore the cam disc/locking disc) is actuated via a triac on the pcb. It changes the relevant water channel to the spray arms. The locking disc has two openings which differ in size. The smaller opening reduces the flow rate to the top basket. The controller receives information on the position of the slide from the micro switch which is actuated by the cam disc. The bad news is that the "water points" are integrated in the instantaneous water heater and it can only be replaced as a complete unit. And it is expensive http://www.espares.co.uk/part/dishwashers/p/1083/0/0/0/1065955/dishwasher-instananeous-w.html Exhaust all other possible avenues before rushing out to buy one & be sure to quote the machine "E" number when ordering any spares. To get enough room to work you would have to remove the tank screws & wedge a piece of wood between the base & tank. I wouldn't split the two completely (you will encounter problems putting it all back together). You shouldn't have to remove the sump,