Bosch SMS4472GB sticking in the wash cycle

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

true
but how does it explains that sometime it works (on some progs) and sometime doesnt?
might be the wire “half” broken and sometime touching sometime not?

[Martin]

Re: Bosch SMS4472GB sticking in the wash cycle

Such is the nature of breaks in the grey plastic ribbon section of that wiring harness.

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

looks like im gonna have a nice nightmare 😀
I guess that the wiring harness is not available as a spare anymore…

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

Ok problem identified and solved.
By following the wiring I found that the step motor was wired to a white cable, and in that particular part of the cycle (where the machine stopped) was not getting any power.
The white cable was going underneath to a sensor, shorting the sensor caused the step motor to resume the cycle.
I removed the sensor and it fell apart in pieces.
Its a mechanical thermostat, with a bimetallic strip and an aluminium housing. The housing was all distorted probably by approx 20 years of service, so the thermostat was not closing anymore at 65°C.
Joining the wires together fixed the problem, now the water is still hot but the machine doesnt hang anymore in the washing cycle.
I looked online for the spare, but it costs too much and the machine works perfectly without so i’ll leave as it is.

[Andy jones]

Re: Bosch SMS4472GB sticking in the wash cycle

You’re asking for serious problems bypassing a stat

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

I ordered one anyway
I found a website that sold it at a reasonable price and put on the order..On ebay I could find only at 40£, this website sold for 2£!
Same identical…

[Martin]

Bosch SMS4472GB sticking in the wash cycle

That thermostat is now obsolete but an alternative can be obtained (part no: 022480). Without it, as Andy says, would be not an option.

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

I noticed..
Without it it doesn’t wash good at all and doesn’t dry at the end..
I guess the heater doesn’t go on much.. If at all… Hope to get the spare soon

[Andy jones]

Re: Bosch SMS4472GB sticking in the wash cycle

That stat controls heater until it gets to 65 degrees by bypassing it you won’t get any heat

[Martin]

Re: Bosch SMS4472GB sticking in the wash cycle

The stat is N/O Andy and closes once the temperature has been reached.

I was led to believe by the OP that is was heating. Now I’m not so sure that is the case and perhaps the element is at fault?

[Andy jones]

Re: Bosch SMS4472GB sticking in the wash cycle

Yes I know that Martin, when the stat closes it feeds the timer motor

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

Does this dishwasher have two heaters? the coil on the bottom heats up nicely…Is there any other “heater” for the water?

[Martin]

Re: Bosch SMS4472GB sticking in the wash cycle

No that’s it.

[assasukasse]

Re: Bosch SMS4472GB sticking in the wash cycle

Then I guess without the thermostat the program runs too quick and there is no enough time to warm up the water…as a result dishes dont come out really clean.
When drying them up, probably the same thermostat hangs the program till the 65C are sensed..without it, it goes too quick and doesnt dry them properly..
I managed to fix the thermostat, or at least appears to be fixed. The contacts were oxidised, i gave a clean with a toothpick and some contact cleaner, on the tester it works and I can trigger it by suspending on top of a glass of boiling water.
I just need to have a try to see how it does in the machine…

[Andy jones]

Re: Bosch SMS4472GB sticking in the wash cycle

There used to be a problem with the other thermostat cycling on and off without getting to 65 degrees causing it not to move on.
On some the fitted a mushroom style cap on top of it

Have a look inside dw. The stat is on the left hand side towards the front between the heater

[Author]

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