I am trying to trouble shoot the timer on a Bosch SMU 3036 Dishwasher as it is not cycling past 3 0’clock (initial wash cycle). The water use to be incredibly hot - therefore the element isn’t getting the signal to turn on and heat the water hot enough to advance the cycle.
I have checked the Element and while it has continuity, it remains stone cold.
I have already replaced the Timer, 2 High-Level Themostats (checked Thermostats and they have continuity) and Temperature Sensor switch (has continuity) - no change it still hangs at the wash cycle and we have to advance it manually to finish the wash - yet dishes aren’t dry because of the element not heating as well.
Only thing to change is the Heating element (but has continuity so I don’t think this is the problem). I really need to find a Bosch SMU 3036 Dishwasher Service Manual or schematic so I can check the timer connections are proper to the thermostats to ensure they are getting the right signal from the timer to heat the Element.
Where would I find this specific manual/ schematic, anywhere on the net?
Any assistance is appreciated.
I saw another manual posted but it is for SHU 3036 - different timer contacts.
Thanks,
JBM
Thanks Gene.
I have totally replaced the wires on the Timer to make sure they were in the right place. I checked for resistance across the (2) Hi-Level Thermotats (.8 ohm), resistance across the Heating element (1 ohm), yet I don’t get a reading across the Themostat (which I believe is because it stay open until sent signal to lose to send power to the Heating element.
I recall someone mentioning to by pass the thermostat and see if the machine runs a full cycle - can this be done safely? If so and the machine does complete the cycle - does this mean the thermostat is no good
Is there anyway I can check across the terminals of the timer to know it is OK?
How do you reset the timer on this machine as I have heard about ?
Any other suggestions are appreciated as I am at my wits end by now trying to solve this as it doesn’t seem to be the Heating Element - although it stays stone cold while washing and it is only the supply Tap hot water tat is washing he dishes currently? It has become more a matter of pride to overcome the machine.
I think you are measuring the resistances incorrectly.
It looks like you are measuring a parallel/alternate circuit path.
The heater should measure much higher than 1 ohm.
A 1 ohm heater would use 120 amps which is way too high.
Did you remove at least one wire from the device you were measuring just to ensure you do not measure an alternate path.
The thermostat contacts should close at 161 F, this tells the unit that the water is hot enough to proceed with washing. Bypassing it so the unit thinks it is full of hot water should not cause a problem.
But it does not rule out other parts.
A crude way of checking it would be to remove it and heat up the face with a soldering gun while measuring the resistance. It should close once it gets hot. Unfortunately this does not tell you at what temperature it is closing.
I had not disconnected the wires from the H-Element, when I do it measures 65 ohms +, which would tell me it is fine.
I heated the thermostat and it did close when heated, but like you say you don’t know at what temperature.
I am going to by pass the thermostat to see if the element heats at least and if the unit cycles - otherwise I am at a loss - I have two timers which are probably good - but I can’t tell for sure and I don’t have any clue as to what to try next?
I have bypassed the Thermostat (temperature regulator - formal part name) and the Regular cycle completes.
I have read on a number of threads the culprit has been known to be the Selector Switch. I have cleaned the contacts/ and tested the Selector switch assembly and have found continuity across 1-2 & 3-4.
The heating element still has resistance reading of 11 ohms.
Having already replaced the timer, (2) High limit Thermostats as well as the Thermostat - short of replacing the Heating element, which I have to believe is good - I am at a loss as to what I can even try next to get the Heating element to heat?
While I can run the dishwasher through all cycles with the thermostat shorted - the water temperature is no hotter than the hot water entering - I am fresh out of ideas or options???
Help is appreciated.
Thanks,
Hi JBM…
I am working on the same dishwasher with exactly the same problem. I replaced the low temp thermo-disc as well as the entire heater assembly.
But the same problem is still there… water heater elements never turn on… even when thermo-disc connections are jumpered (to have clock motor complete the wash cycle). Did anybody ever get back to you with the correct solution to this truly elusive problem? I spoke to Bosch support, but the people that man the phones are not very technical. You would have to talk to one of the designers of the machine and that ain’t gonna happen.
Hi Rennman, I never did get a reply - so I have jumpered the thermostats and it seems to work fine, with the exception of the drying cycle.
We will be replacing it soon, given it is around 15 years old so I am just postponing it for as long as I can.
Interesting that nobody (not even Bosch phone tech support) can tell you what causes this common problem on this purely electro-mechanical machine (no micro-processors, no circuit boards, no digital stuff at all). I guess the only one who knows the answer is the German engineer who designed this dishwasher and even then I’m not so sure. But isn’t there anybody out there in forum-land who has solved this one. I find it hard to believe that there’s no one. Thanks for answering JBM.
Hi Rennman, Gene at the start of the thread was the most helpful and directed me to the schematic which I used to troubleshoot the circuitry.
Otherwise I am in total agreement with you - having changed all the parts to no avail.
Take care,
Blake
You said "in the 3 o’clock position, you must have a “timer knob”. I had this machine like that but it turned out that it really is not a clocked timer constantly running like gears and a motor. Instead the motor would turn on when it gets a signal of power and off when the power cuts off, so it would turn the knob fast basically when it was time to go to the next phase. Therefore it was still computer chip fully operated, not a timer running. However, behind the knob it has multi teeth to which complete the curcuit of multi switches in different patterns for different wash combinations. I BET at least one of those switches is dirty and its one that gets pressed right at the 3 o’clock position. Not easy to clean, need small strips of crocus cloth. You have taken apart the front panel yet, right? If that’s not it then it must be your computer chip or circuit board is failing somewhere. Maybe some capacitors on the board. I am going to put a layer of fiber glass between the wash wall and the circuitry to lessen heat and corrosion.
JBM,
Did you ever get to the bottom of this?
My Bosch SMU 2046 has the exact same problem you described about getting stuck in the wash cycle, and I noticed the heating element not coming on.
I have run in this way for a few weeks now. . . me advancing the dial by hand after it has run in wash mode for what seemed long enough, and then advancing it by hand after the rinse cycle when it would get stuck there too.
Now it seems it is heating the some, but it still gets stuck in the wash cycle.
I would like to fix it if possible, but sounds like I should maybe just bite the bullet and get a new DW?
I had a similar situation on an SPI2322/07. The thermostat contacts that are supposed to close at 85°C didn’t. So the green wire from the timer lug that is soldered (through a black wire) to the timer motor never got Neutral after the timer stops to heat the water → you get a steam engine - it just churns on and on a the same timer position.
I followed the green wire down to the thermostat and found it is a two-tier unit, having four contacts.
I took the thermostat off the heater assembly (it is inserted into a rubber bunghole in the top of the heater) and did not want to spend €60 on a new one. so I took it apart. The top comes off easily and there is the N.C. contact that controls the heater behind it. In order to get at the N.O contact that controlls the Timer Motor you have to “take off the top floor” - I drilled out the two copper rivets holding the assembly together and cleaned the contacts of the N.O contact. Don’t lose or break the thin ceramic “push-rods” coming from the click-disk in the basement.
Re-assembly using 13A stripped copper wire to hold it all together, stuck it back into the bung-hole.
Works just perfectly now!
[quote=ericbecky;862586]“Re-assembly using 13A stripped copper wire to
hold it all together, …”
Can you describe what you did in a bit more detail?
Once I drill out the copper rivets, I’m not sure how the copper wire will
hold things in place.
Maybe you drilled a hole through the entire plastic assembly an twisted
the wire together to hold it in place? Hmmm…
I was hoping to figure it out prior to drilling out the copper rivets.
Otherwise I’m not quite sure how I’ll hold everything in place.[/quote]
I did NOT drill through the entire assembly but twisted the copper wire around the left and right half of the plastic (bakelite) part holding the contacts whilst clamping the two halves (tiers) together in the vice, and then soldered the copper wire together so everything is being held together securely. I left the headless copper rivets in their holes so as to have perfect alignment of both bakelite parts together with the metal bottom of the unit.
You could send me an email personally if you want nick at reflex dot at (the 2nd at stands for Austria). I am having trouble getting into this board, it always slips away and becomes white!!
[quote=ericbecky;862586]“Re-assembly using 13A stripped copper wire to
hold it all together, …”
Can you describe what you did in a bit more detail?
Once I drill out the copper rivets, I’m not sure how the copper wire will
hold things in place.
Maybe you drilled a hole through the entire plastic assembly an twisted
the wire together to hold it in place? Hmmm…
I was hoping to figure it out prior to drilling out the copper rivets.
Otherwise I’m not quite sure how I’ll hold everything in place.[/quote]
I did NOT drill through the entire assembly but twisted the copper wire around the left and right half of the plastic (bakelite) part holding the contacts whilst clamping the two halves (tiers) together in the vice, and then soldered the copper wire together so everything is being held together securely. I left the headless copper rivets in their holes so as to have perfect alignment of both bakelite parts together with the metal bottom of the unit.
You could send me an email personally if you want nick at reflex dot at (the 2nd at stands for Austria). I am having trouble getting into this board, it always slips away and becomes white!!
nick at reflex dot at (the 2nd at stands for Austria). I am having trouble getting into this board, it always slips away and becomes white!!