Bosch Avantix dishwasher, not draining. water detect switch?

[HankMcSpank]

Hi,

After my dishwasher cycle has finished, I’m opening the door to see dirty water still at the bottom of the dishwasher chamber.

So I start a new cycle….thinking that the first part of any dishwasher cycle is for the dishwasher to check there’s water in the washing chamber & if so, pump it out? But when I start a new cycle (with the dirty water still in the dishwasher), I’m not hearing any drain pump humming (suggesting the pump isn’t being activated – either that or it’s faulty!), which makes me think there might be a water detection switch in play? Perhaps if this switch isn’t detecting water, then that’s why the water isn’t being drained? As an aside, I had the base off the other day (to sort a leak – pump wasn’t seated properly after traonsport) & manually lifted the flood detect float/switch & the dishwasher drained, so I don’t think the drain pump is faulty…there’s something else going on here I think.

Dunno, just a theory.

Grateful for your advice 🙂

the model is Bosch SGS45A02GB

[electrofix]

Re: Bosch Avantix dishwasher, not draining. water detect swi

if you lift the float and it drains its cant be the pump

sounds like it may be a prog problem or a wire break between timer and pump

Dave

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Thanks.

So (being new to dishwashers), is my line of thought broadly correct…i.e. that the program start sequence is like this…

1. Power on
2. Program start – detect if any water is in chamber
3. If so, drain water (apply mains electricity to drain pump)
4. Once ’empty’ is detected, start program cycle

…because if so, I’d have thought it would be the water detection part that’s going wrong? Is that some form of switch that I can spoof temporarily? (to help progress the diagnosis)

What’s actually happening is that even though the dirty water isn’t draining (from the previous cycle), the dishwasher is starting to fill with new water when a new cycle is started..

I don’t suppose service manuals exists for a bosch avantix? (or even a wiring diagram?the model I have looks like this – http://s3-eu-west-1.amazonaws.com/media … 5A02GB.jpg )

[electrofix]

Re: Bosch Avantix dishwasher, not draining. water detect swi

no all dishwashers start with a drain cycle before it fills. no water detection so starts to fill

your problem is with the pump circuit

Dave

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Hi Dave,

Thanks for the input.

So dishwashers don’t have any water detect sensor to establish if there’s water still in the wash chamber ….I’m figuring therefore the wash chamber ‘drain aspect’ is a very basic timed setup….i.e. at the beginning of every cycle, turn the drain pump on for say 20 seconds – then start filling?

[electrofix]

Re: Bosch Avantix dishwasher, not draining. water detect swi

no water is counted in so unit know how many litres have been put it. All cycles drain first. Some later units use the pump to detect water has drained but this model does not

timer or wiring to pump is first check

Dave

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Thanks Dave.

>> timer or wiring to pump is first check

As mentioned earlier, the drain pump starts & water drains out when I lifted the flood detect float switch the other day, so I know the pump is ok, but I’d have thought the wiring to the drain pump would only be two wires (live/neutral) …I am going to have to get underneath again to check – but if this is the case, then if the pump starts when I lift the flood detect float switch, then presumably it can’t be wiring to the motor – concur?

[Martin]

Re: Bosch Avantix dishwasher, not draining. water detect swi

HankMcSpank wrote:– but if this is the case, then if the pump starts when I lift the flood detect float switch, then presumably it can’t be wiring to the motor – concur?

As Dave has said (twice) the drain pump should be activated by the control unit (aka timer) at the start of all programs. If it does not and yet pumps once the float is lifted then the primary suspect is the control unit OR a wire to it from the pump has come adrift.

When you messed with the pump did you knock or pull a wire off? Are the control unit connections fully in place? Has a wire between timer and pump broken on the wiring loom?

That such cover all likelihood I would think 😀

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Martin wrote:As Dave has said (twice) the drain pump should be activated by the control unit (aka timer) at the start of all programs. If it does not and yet pumps once the float is lifted then the primary suspect is the control unit OR a wire to it from the pump has come adrift.

Because I won’t be able to look at this until tomorrow, I was just trying to cover all eventualities before I revisit, hence labouring the point asking about wiring to the motor (i.e. whether it’s just two wires going to the drain pump – if so, these wires are supplying mains to the pump when the anti flood float switch is activated so it can’t be the wiring & therefore that only leaves the control unit)

Thanks for your input…I’ll have a look tomorrow

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Ok, I’m puzzled.

At the start of a cycle everything works as it should, the dishwasher drains (which must mean the drain pump is working + the wiring , there must beno blockages – the pipes are clear etc.) – but at the end of the cycle, there’s water left at the bottom of the wash chamber ….could this therefore be the control board? (i.e. not sending mains voltage to the drain pump at the end of the cycle)

[electrofix]

Re: Bosch Avantix dishwasher, not draining. water detect swi

or a broken wire between the pump and the timer that is intermittent

Dave

[Martin]

Re: Bosch Avantix dishwasher, not draining. water detect swi

…..OR the pump is clapped out and sticks when very hot water is in the tub. If there is any lateral movement of the impeller then it is worn out (or knackered as we say in the trade 😉 ) If the dishwasher is more than 5 yrs old the pump will be so afflicted. 🙁

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Interesting – funny you should mention that….with our old dishwasher if the water was too hot it wouldn’t empty (this is according to my wife when I was telling her about the dishwasher not draining), so this is a strong line of enquiry with this one that we’ve just purchased secondhand to replace the old one!

Presumably when you say “lateral movement”, the impeller shouldn’t have any wiggle? (a bit like checking the wheel bearings on a car by trying to wiggle the tyre?). f there is lateral movement is it a whole new pump required or can the impeller be replaced on it’s own (for a non wiggle version!)

[electrofix]

Re: Bosch Avantix dishwasher, not draining. water detect swi

new pump

Dave

[HankMcSpank]

Re: Bosch Avantix dishwasher, not draining. water detect swi

Just a quick bit of feedback.

On a quick wash cycle (20m), there’s water sitting in the wash chamber at the end of the cycle.

On a standard wash (1h20m) …the wash chamber is completely empty at the end of the cycle..

Therefore, the short term fix for this is not to use a quick wash cycle!

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