Bosch dishwasher – faulty on/off switch?

[mikevernon]

My SWS45A12 dishwasher is showing no lights at all on the control panel and not running.
There is power at one of the wires going to the switch, but I now think the on/off switch itself may be the cause of the problem.
I’ve removed the switch to test it, and the two terminals nearest to the centre of the machine appear to do nothing (there are 6 terminals and 6 wires connecting to them). Neither of these two terminals have continuity with any of the other terminals, whether the switch is in the off or on position. I can’t think of any explanation for this other than a faulty switch. Does that logic sound correct?
The switch terminals could just be corroded so I’m trying to pull the switch apart to have a look, but so far without success.
Has anybody ever succeeded in taking the on/off switch apart, and if so can they remember how to do it?

[timdowning]

Re: Bosch dishwasher – faulty on/off switch?

Similar models of your dishwasher with your fault is normally due to one of the ‘chips’ on the control unit failing.
You have to look carefully to see that the top of one chip will have blown. This is normally caused by the heater / diverter assy.

I cant give you a reason to why the switch ‘rings’ out like that but it is normal.

If you have power to the switch & contol unit then I would say the fault lies with the contol unit.

Power off of course when testing / working on machine!!!!!

[mikevernon]

Re: Bosch dishwasher – faulty on/off switch?

Thanks for your reply Tim. If it is likely to be the module at fault then I’ll scrap the dishwasher, which is a shame because it is in lovely condition otherwise.
But I’m still not convinced about the on/off switch. There are two terminals which are not connected to the other four terminals, and are not affected in any way by the switch being on or off. These terminals are connected by white wires to the control module, so surely they must have some function? That suggests to me that there is a fault within the switch.

[Martin]

Re: Bosch dishwasher – faulty on/off switch?

mikevernon wrote:That suggests to me that there is a fault within the switch.

I very much doubt that though I’ve never heard of an SWS45A12 before. 😕 (I reckon you have the model number wrong)

99{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} likelyhood it is a Control Module failure, only 1{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} on/off switches fail.

[mikevernon]

Re: Bosch dishwasher – faulty on/off switch?

Martin. Sorry, the model number starts with SGS, not SWS.
Perhaps I didn’t make my question clear enough. I wanted somebody to explain why there should be two pins on the switch which are not connected to any other pins and are not affected by operating the switch. If these two pins are redundant, as they appear to be, why do they have wires connecting them to the control module?
Does anybody have one of these 6 pin switches handy? If so I’d be really grateful if they could check to see if the two pins at one end are redundant. The part number on the switch is 5600.041.906

[Martin]

Re: Bosch dishwasher – faulty on/off switch?

mikevernon wrote:Martin. Sorry, the model number starts with SGS, not SWS.

If you can give me the full and complete model number I can look up the respective wiring diagram. There are 3 different SWS45A12’s listed and all of which are not made for the UK market. So I guess you’re either not in the UK or you bought it whilst abroad? 😕

[mikevernon]

Re: Bosch dishwasher – faulty on/off switch?

Thanks for your kind offer of help Martin. The full model number is SGS43A12GB/27. Sorry I got it wrong earlier.
It is a UK model dishwasher.
The 6 pin on/off switch seems to be common to a few different models.
I look forward to hearing from you.

[Martin]

Re: Bosch dishwasher – faulty on/off switch?

mikevernon wrote:The 6 pin on/off switch seems to be common to a few different models.

Indeed they are and I’ve checked your corrected model number and my earlier advice still stands. By all means buy and fit a new switch (lot cheaper than the Control Module for sure) but I’m certain the fault is with the Module and not the On/Off Switch….OK?

[mikevernon]

Re: Bosch dishwasher – faulty on/off switch?

Hi Martin. I thought you were going to consult your wiring diagrams to find out the function of those two pins on the on/off switch. I still think that might be the cause of the problem.
I’ve always disliked the approach of just replacing parts in the hope that they might be the cause of the problem, rather than methodically testing components to identify a faulty one. That is why I’m reluctant to replace either the module or the switch unless I can be sure that they are faulty.
Regards
Mike

[Martin]

Re: Bosch dishwasher – faulty on/off switch?

mikevernon wrote:Hi Martin. I thought you were going to consult your wiring diagrams to find out the function of those two pins on the on/off switch.

Please forgive the attention slip…..I’ve looked at the wiring diagram and all 6 wires, all 6 connections have functions. The 2 that you are puzzled over most likely are the 2 that activate the relay on the main Control Module.

I hope that helps you further in reaching the same conclusions as I have already? 8)

[mikevernon]

Re: Bosch dishwasher – faulty on/off switch?

…..I’ve looked at the wiring diagram and all 6 wires, all 6 connections have functions. The 2 that you are puzzled over most likely are the 2 that activate the relay on the main Control Module.

Thanks for looking, Martin. If those two wires activate the relay on module, then surely they should receive power when the on/off switch is turned on? They don’t, so surely that supports my supposition that the switch is faulty?

[kwatt]

Re: Bosch dishwasher – faulty on/off switch?

I don’t know these machines as well as Martin does for sure but, the power switch is listed here and not exactly the cheapest of parts to take a punt on. I would have thought power switch on the face of it but I will bow to others greater knowledge of Bosch dishwasher problems. 😉

K.

[nomadPaul]

Re: Bosch dishwasher – faulty on/off switch?

IIRC , i think you’ll find on this on/off switch that contacts 1 & 2 will only make when the door is actually closed . Does it have a bar between the switch and the door lock ? If you can reach the contacts with the switch in situ , then test it again with the door closed ….POWER OFF OF COURSE.

[mikevernon]

Re: Bosch dishwasher – faulty on/off switch?

Hi nomadPaul, and thanks for your contribution.
I understand your point exactly, and the switch does indeed have a mechanical linkage to the door handle. However, this linkage physcally prevents the switch from being turned on when the door is open, and since I’m testing the switch off the machine I have made sure that the linkage is in the “door closed” position so that I can operate the switch, if that makes sense. So although that might have provided the explanation for pins 1 and 2 being inoperative, it still leaves me in the same position and I still think the switch is the likely culprit.
Thanks also to kwatt for the list of machines with the same on/off switch. That could be very useful.

[Author]

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