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FIXED SHU66C02UC Bosch Dishwasher repair in doubt

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Premium Member
May 24, 2014
Mid Atlantic
Model Number
We had trouble free 6 years with our bosch dishwasher. Last month the control module relay fry( K1 relay-smoked/burned the old board ). Just before the relay burned, it would stay on the last min of the counter for a while. Everything was working prior to the control module board frying.

1. Replaced the Control module and the circulation pump did not come on. It just fills with water and drains a little, kinda pulses with water in and draining. When you cancel the cycle it drains fine and turns off. Would say you could smell an electric burning type odor when this was first installed, but that could be from the old board. The old board seemed to get very hot when the relay burned. We liked this dishwasher and felt it was worth replacing the Circulation pump and have another 10+ years of life.

2. Replaced the Circulation pump with a brand new one and it does the same water in and draining! I tried adding a couple cups of hot water when it was filled with water to see if the increased water level would cause the circulation pump to come on, but no changes. The old motor seemed to be fine, no play in the bearings or impeller. This is turning into an expensive project and I am still washing the dishes by hand.

3. Let's throw more parts into the dishwasher. This evening, replaced the Water heater assembly, which included the NTC sensor, aqua sensor, and other switches that are part of the Heater assembly. New float switch and a new water inlet valve. Does the same thing, fills and drains and the circulation pump never turn on! The dishwasher drains fine when you cancel a cycle and the various run cycles appear but the circulation pump does not work. The drain pump seemed kinda hot after running for a while constantly draining/filling.

At this point I am down to a few original parts such as the drain pump and soap dispenser. Also the 186963 PC board(just a display or does it also control the circulation pump???) and the wiring. The wiring looks and feels ok and all the wires are connected.

Starting to feel that I should have ordered a new dishwasher when the control module burned up. Has anyone run across this problem before?


Missing a couple of digits.

I got SHU66C02UC-14 to come up for me.

First thought was a bad new part since it happened right after the repair:(
Should also check the float/float switch in case the d/w thinks it is a float mode with water in the base....that prevents the wash from coming on and drain pump only will work. If the float checks ok, I'd be inclined to try another board.

Control unit

SP427 said:
... which included the NTC sensor,.....
Part of the NTC thermistor is the high limit thermostat. Check the two red wires are connected correctly in the right spot. You can check the high limit t-stat at the control if you have your wiring diagram. Make sure you got the wires on the float switch correctly and in the right spot. With all the parts you replaced there's a very good chance it's miswired somewhere. Those are the two places it's easy to get the wires backwards.
Hello, Appreciate the replies. The full model number is SHU66C02UC/40.

Realize ordered a few extra parts. Especially when I ordered the heater assembly. Thinking it would be mechanically a new machine and perhaps the heater going bad caused the relay to burn. The wires are hooked up correctly, took time to make sure everything matched one wire at a time. The problem has persisted thru the parts being added in steps over the last few weeks. I turned the machine back on after replacing numbered part below.

I had a factory auth service for the control board. When the circulation pump would not come on, they just left. Took two days off for the disappointing service call and once I had a chance to read what others had said about company online, many zero and 1 star reviews. I decided to it was less frustrating to put the parts on.

1. Control board (Bosch # 00447325)
2. Circulation Pump (Bosch # 00661792)
3. Heater assembly (Bosch # 00480317)
4. Float switch (Bosch # 00165256)
5. Water inlet valve (Bosch # 00425458)

Would a defective(but working) drain pump cause the circulation pump to not engage? Previously, could not find a manual online for testing steps. The float switch on the left side seems to be wired correct.

Thanks again
Do you have a VOM that can measure ohms and check continuity? It should also be able to measure VAC and VDC. I'll tell you how to check it if you do. Bosch sucks when it comes to wire diagrams and schematics. It takes some time to decipher their diagrams. If you don't have one, (considering all the parts you've replaced already, I'll assume not) then you need to get one. Without a VOM it's just replacing parts until one fixes it and you're already doing that.
Digital Multimeter DM10T

A different control to the one I posted...

Control unit

Would a defective(but working) drain pump cause the circulation pump to not engage?

Not normaly no.

The float switch on the left side seems to be wired correct.

It is not stuck up and no water in the base?

No water in the base and it you lift the new float switch. The dishwasher stops filling and starts draining. The old switch operated the same way.

Starting to think the new control was defective, unless part of the wiring is bad. Have moved the wires slightly when the dishwasher is filling with water and the wires seem ok. What is the next step, I have an inexpensive multimeter?
I found the repair manual on this site. Holding the two buttons and turning on the power switch. The LCD shows number 4, while the two red lights above the cancel/drain blink .
Last edited:
Check the on-off switch. The on/off switch turns the dishwasher on and off and is crucial in resetting controls. Contacts 5 & 6 reset the control. Whenever a control won’t reset or won’t go into wash programs, check the on/off switch and jumper. Replace switch and jumper if they’re faulty. Remove power and with the on/off switch in the ON position you should have continuity between 1-2 and 3-4 and 5-6 (if 5-6 is a reset button you may need to press it to show continuity) and 3-5. In the OFF position check the jumper for continuity between 3-6.
That's not the manual for your model. The only model close to yours was SHU68. Here's the wiring diagram for that model but no tech sheet. Is yours gone?


  • SHU66C SHI66A Wiring Diagram.pdf
    1.5 MB · Views: 390
Bosch SHU66.jpgBosch SHU66.jpgBosch SHU66 back2.jpg

Hello, The wiring diagram is scanned to the attached PDF's. I am going to test the on/off switch today. What are the items to test next? The dishwasher has 120V at the terminal box, guessing that is a good place to start. Thanks
Sorry it took so long, I had to go over part of the wiring diagram to make it easier to see. (I'm getting old...lol) If the on off switch checks good, the board must be bad. I marked the diagram blue for the neutral path and red for L1. Neutral is at the drain motor and circulation motor from the on off switch. L1 is supplied to the drain motor and circulation motor from the board relays. The drain motor works so if the circulation motor doesn't have 120 VAC going to it, the board is bad.
SHU66C Control.jpg
Hello Rick,

What great advice you shared with me, I appreciate the time it took to read the diagram and post the switch circuit. Incorrectly thought the switch was good since the dishwasher turned on, could it be that simple! The very cheap centech multimeter is faulty, kept getting zero continuity readings on the switch for every terminal.

Borrowed a friends high quality Fluke meter tonight. If the terminal order is from left to right. We have continuity for 1-2, and 3-4. Terminal 5-6 you press in the the switch in for continuity! In the off position, zero continuity between 3-6. Continuity for 3-5 appears to be zero. The 5-6 terminals also have a slight brown residue on the tips of the terminals. I am going to check a local supplier tomorrow and see if they have the switch in stock or I am going to order one from the Repair Clinic. Will keep you posted on the progress. Thank you again.
zero continuity between 3-6.
There should be continuity between 3 and 6 if the switch is on or off. This is the jumper wire. I will mark it on the diagram.

Continuity for 3-5 appears to be zero.

Terminals 3 to 5 will only show continuity when the switch is in the on position and the 5 to 6 contacts are closed. This is what resets the control board.
SHU66C Control.jpg
Update, installed a new bosch switch. The Dishwasher has the same problem, the circulation pump does not come on. Guessing the new control board was defective or something else is faulty. Will update on the replacement board or if this dishwasher ends up in the recycle pile.
Hello Rick, Not sure what you mean when you say jumper. The wire loop in the wiring harness, from Terminal 3-6? I tested the switch terminals, please clarify if the test is for the wiring harness or if I should have added a piece of test wire to the switch between terminals 3-6 to test the old switch. Thanks again.
Yes, that jumper wire needs to be connected to the switch and it needs to show continuity or the switch won't reset the board.
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