Bosch water heater

[waidulis]

Hi all,

I am newbie in this forum and actually “green” on electronics, although usually trying to fix all the stuff by myself. But now I am stuck and would like to ask you for the help in my fixing. My Bosch dishwasher not heating water anymore (error code 02), although everything other works and washing program finishes.

Probable malfunction could be in Control module, or water heater itself. Control module looks fine, any burn signs, after turning machine on it shows 60v voltage from Control module contacts.

Now about water heater...as you see in picture, it consist of water pump (on the right) and heater element (on the left). Water pomp coil winding shows 54 oms, heater element coil winding shows around 20 oms, so I tended to think they are OK.

Now, I am not sure, that is on the right next to heating element contacts? This little chain is closed and goes nowhere. Is it something like thermistor, what probably gives signal to Control module and switches heating element off in order not over burn it? What are these two little electronics components, showed in picture 3 (from chain scheme it is obvious, these to components duplicates each other, probably for assurance)?

These contacts do not show continuity, although periodically it shows 1782-1900 measurements and instant returns to no connectivity. Should it be like that? I tend to think something is wrong here...How you would recommend to test this little chain and these two components without putting it to dishwasher?

Thank you for you help and sorry for my English as well

Pictures:

[helius]

They look like thick-film carbon resistors and are probably used for temperature sensing. Is that side of the unit submerged in water?

[waidulis]

They look like thick-film carbon resistors and are probably used for temperature sensing. Is that side of the unit submerged in water?

No, water flows only in the inner part of the heating element and pump.

Probably yes, After some reading it could be thin-film resistors for temperature control. On 200kOm Multimeter they both shows 11.4. Is it good? Heating element coil wiring on 200 Om on Multimeter shows 19-20, and that is ok, as I saw on youtube about these heaters.

So, it means that Control Module is Mulfunction?

[waidulis]

So, it seems water heater and termistor are ok. Bosch describes error 02 as: If you get the error E 02 on your Bosch Dishwasher then the primary relay on the power module has failed and it is working off the saftey backup relay. You will need to replace the power module.

How do you think, is it worth to try changing only relay? The new Control module will cost over 100 euros. Is it possible to check which exactly relay is mulfunction? On the chain to contacts, that leads to heater?

[Teledog]

Perhaps slightly off topic, but same brand.
Bought a Bosch dishwasher, ..err. ..smelly dish "rinser"??
Worst F'n appliance I have ever purchased in my entire life!!! Really!!
99% of the so called "reviews" are shills.
Bosch and their dealers will not allow/refuse negative review postings on their websites.
Good luck!
..end rant..

[jh15]

Make sure your strainers are cleaned an not loose.

Recently had wife that left center strainer loose and clogged the spinners. Not the first time.

Was told it stinks by dealer early on that it did not vent heat for energy efficiency.

Weird, once again cleaning strainers that were again loose, the thing actually washes well and doesn't stink as much for months now. Maybe hiding places for garbage internally.

Was about to replace it.

[frozenfrogz]

How do you think, is it worth to try changing only relay? The new Control module will cost over 100 euros. Is it possible to check which exactly relay is mulfunction? On the chain to contacts, that leads to heater?

Checking the relays is straight forward and easy. You need a multimeter to check continuity and a 12VDC source.
Omron G2RL datasheet (the Schrack one can be found via google/startpage/yahoo also, just search for the part number and "datasheet").
The coil does not have polarity, simply apply 12VDC and the relay should switch with an audible »click«. Check the pinout to trace what gets switched where. Check continuity (between pin 3 and 4 -> datasheet) without power supplied to the switching coil and also when coil is powered. Relays usually fail from contacts "baking" together or a burnt coil. In both instances the relay does not switch the contacts any more.

If it is not a relay (chances are high one of those failed -> mechanical part rated for 50.000 operations), I would continue checking the relays actually get fed 12V for operation or if something in the power supply circuit failed.

[tooki]

Perhaps slightly off topic, but same brand.
Bought a Bosch dishwasher, ..err. ..smelly dish "rinser"??
Worst F'n appliance I have ever purchased in my entire life!!! Really!!
99% of the so called "reviews" are shills.
Bosch and their dealers will not allow/refuse negative review postings on their websites.
Good luck!
..end rant..

I have a Bosch dishwasher in my apartment (it’s what came in it) and I’m very pleased with it. But as modern energy-efficient machines, they use complex heat exchangers and stuff that do offer more nooks for gunk to accumulate. It’s essential to regularly use machine care cleaner. (It’s a liquid or powder that you run without dishes in a hot cycle.) And before you do, be sure to clean out all the filters, and to remove the spray arms and clean them out as well. If it hasn’t been done in a while, you may need to do it more than once. This maintenance should be done about every 2 months in normal use.

[GeorgeOfTheJungle]

 I have an AEG "Silence Sensormatic" that has ~ the same heating element as your Bosch and a very similar main board too. The relay of the heater (exactly like the one in your pictures) failed once but it was a cold solder joint that was ~ like this
 
 I fixed it and the heater has never failed again. But as it's got gremlins inside many other things have failed over the years. It's the most expensive but not the most reliable dishwasher I've had. When it works (several years in a row now, touch wood) it works very well.

[Naguissa]

I have an AEG "Silence Sensormatic" that has ~ the same heating element as your Bosch and a very similar main board too. The relay of the heater (exactly like the one in your pictures) failed once but it was a cold solder joint that was ~ like this
 
 I fixed it and the heater has never failed again. But as it's got gremlins inside many other things have failed over the years. It's the most expensive but not the most reliable dishwasher I've had. When it works (several years in a row now, touch wood) it works very well.

I have a Candy one (italian brand). It's the.mos simple and reliable unit I've never seen.



Enviado desde mi Jolla mediante Tapatalk

[Cyberdragon]

*sees large black rectangular flat things*

What are those?!

[frozenfrogz]

*sees large black rectangular flat things*

What are those?!

My guess would be motor drivers / power modules, maybe STMicroelectronics SLLIMM or Mitsubishi DIPIPM.

[Teledog]

I have a Bosch dishwasher in my apartment (it’s what came in it) and I’m very pleased with it. But as modern energy-efficient machines, they use complex heat exchangers and stuff that do offer more nooks for gunk to accumulate. It’s essential to regularly use machine care cleaner. (It’s a liquid or powder that you run without dishes in a hot cycle.) And before you do, be sure to clean out all the filters, and to remove the spray arms and clean them out as well. If it hasn’t been done in a while, you may need to do it more than once. This maintenance should be done about every 2 months in normal use.
[/quote]

Have used several dishwashers over the years.
They were always called  "dishwashers" and always washed and dried the dishes...sterilized actually!
Not once have I had to "clean filters" or "do maintenance".
Energy efficient? How is it rated? by the hour?
It takes 2:20 for a simple (wet dishes) cycle with the bosch. Compress that energy rating to 45 minutes, is it really more efficient?
Old dishwasher, throw in the dishes, granular detergent and 45-60 minutes later..done! Had to use gloves to extricate the hot dishes!
The crap went down the drain..all by itself! Funny that!
They've lasted well over 10 years (older ones, almost 20) with semi daily use.
ZERO "maintenance".
I guess the manufacturers are now "training" people on how to dry their own dishes, clean and maintain their products on a regular basis?
Does your car manufacturer now tell you that you have to push your newly purchased car down the street? ("We never said it actually works!")

I find it hard to believe that these manufacturers are actually "training" purchasers for their lousy substandard products..and the purchasers are actually going along with it!!!??
 /end bitch

[tooki]

You’d do well to learn about why things are the way they are before going off on a silly rant. The manufacturers are making the machines this way because energy use laws are requiring them to do so. Consumers buy them because they are the only machines on the market.

The energy consumption is calculated per complete cycle. Modern machines take FAR longer to do a cycle, but use far less power, such that the total energy consumed by a load is significantly lower. (For example, my heat pump clothes dryer uses 1/4 the power of a conventional one, but takes twice as long, resulting in total energy consumption per cycle of 50% of the conventional dryer.)

They still dry dishes. My dishes come out dry. I wouldn’t want it to heat things more than it does (certainly not to “sterilize” temperatures — though I think that was a myth anyway) because I wouldn’t want plastic things like Tupperware to melt.

Car manufacturers face similar efficiency and emissions requirements, which is why modern engines are so complex and can’t really be serviced by hobbyists any more.

So yeah, you need to brush up on why modern things are the way they are. You’re stuck in the past.

[Teledog]

Show me your RoHS "energy efficient" appliance in 10 years..

[tooki]

It’ll probably be replaced by then, since modern stuff doesn’t last. What’s your point?

[waidulis]

So, I checked all the relays, all of them working (put 3v DC on them, they have audiable "click"). Didn't check, if they get 12vDC from board, because in any way I will not be able to determine why they not getting it.

The interesting thing is, that the middle relay do not have continuity then it is opened (and so should be), but having 1200 multimeter readings on 2000kOm settings in opened position (other relays do not have that). Probably the relay itself is good, but somehow part of current flows around contour and bypasses the relay. I don't know if it should be like that, or not.

In any way, it seams I will need professional repair

[GeorgeOfTheJungle]

Those realys cost just 3€, you could replace them all and see if it works, you'll save 88€ if it does, lose twelve if it doesn't :-)

https://www.mouser.es/ProductDetail/Omron-Electronics/G2RL-1A-E-HA-DC12/?qs=jvGqVfHPSOLDrOSOSbkfPg==