Bosch Dishwasher has gotten me puzzled.

[JamesonEpp]

A Haiku to get you in the mood:

My Bosch Dish Washer
Is Frustratingly Stuck
At A Loss For Words

 

Bosch SHS5AV55UC/22 Dishwasher. 
I'm a relatively intelligent and intuitive person, and a teacher, so also very patient. But this one has me stumped. I've got a multimeter and testing cords, and have checked every component to the best of my ability, and replaced parts in an attempt to troubleshoot. Each individual component seems to work fine outside the machine when bench testing, and switches send signals as they are supposed to. Here's what I have done / think I know so far: 

 

Initial problem: not draining. > Replaced drain pump last year (solved) 

Problem: not draining, pump works > Bosch phone call > replaced main control board (July 2022) (solved) 

Problem: not draining > test pump (faulty) > ordered new pump **parts arrived damaged, reordered and replaced twice** > (not fixed) > Bosch phone call > replaced main control board (Feb 2023) (not fixed) 

Problem: not draining > service call to technician > diagnosed main control board > reordered new control board > replaced (Feb 15 2023) (not fixed) 

Problem: water inlet valve does not activate > replaced, bench tested OK > does not activate with drain pump 3 > drain pump 3 works outside machine when attached to control board AND inlet valve activates (puzzled)

Problem: drain pump installed (working for first part of cycle > manually activate water inlet valve when signal sent from control board (machine fills, circulation pump runs, drain pump cycles) (puzzled)

Tested: water level switch at back (working, sends signal) 

Problem: not draining: WORKING water inlet valve installed, WORKING drain pump installed, Control Board 3 (working?) installed > GoPro and a light inside the machine: run Auto cycle > runs program as follows: 

0:00 drain pump 3x

1:00 water inlet valve (fills sump to level of screen filter)

1:30 circulation pump (arm moves)

2:00 water inlet valve (fills tub to wash level) 

2:30 circulation pump (arm moves)

6:30 circulation stops - no sound from machine, water level at wash level

7:30 sounds of drain pump attempting to cycle

8:30 beeps - sanitized light blinks indicating error (was told this was drain pump by Bosch

 

 

Argh! As you can imagine, after three months this is becoming frustrating beyond imagination. Any help or guidance as to next steps are appreciated. 

Thanks!

Jameson

 

 

 

 

[Vance R]

For the drain issue the maybe something in the drain check valve or drain hose causing an intermittent blockage. Remove the drain hose and drain check valve to look for foreign objects. 

[JamesonEpp]

All lines are clear. Snaked out the drain lines all the way to the main drain under the sink. (Yes I cleared that as well) 

[Vance R]

No worries, my tail then. Had a Electrolux dishwasher with intermittent drain, replace drain pump twice, snaked the drain tube everytime. Still intermittent draining, gave up and ordered drain tube due to the builtin check valve. Replaced the hose then asked the customer if could cut open the old drain hose, she said sure. Found a clear plastic foot from a counter trivet stuck in the check valve. The snake would just past thought without any issues. Impossible to see due to color and a snake would just flip it sideway and pass through. If you problem persists maybe worth a look as your check valve is separate from the drain hose.

[JamesonEpp]

Thanks for the suggestion Vance.

Took off the hose this morning, it’s clear. I can run water or air through in either direction - and can’t feel or see a check valve. Either it’s stuck open or isn’t there. (I don’t have a disposal anyway).

Ran through a rinse cycle, and right at the end when the drain pump was supposed to cycle, it just sat there and clicked. (About 80 pulses per minute)

 

[Vance R]

From the exploded view the check valve is in the sump nipple, item # 431. Should be viewable form the sump. 

[JamesonEpp]

Nothing stuck in the valve, opens when I push a straw through from the sump side. 
 

here’s what it sounds like at the end of a cycle video. The drain pump and circulation pump does run at the beginning of a cycle if the dishwasher is empty. It will not run if the tub is still full of water however. 

[Vance R]

Listened to the video the drain pump is ticking like it is trying to start. Since it runs with no load we come back to control issues.  Remove the cover item 0434 in my picture, check for burrs in the cover and sump. When reinstall the cover make sure it is tight.  Which error code are you getting 24 or 25? If the drain pump cover is good you can try a reset. 

[16345Ed]

Little plastic Parts 433 and 434 must be installed perfectly or it won’t drain. 

[JamesonEpp]

434 and 435 fit snugly and look fine to me. 
Tried the reset option, same result. 
FYI, there is no digital display on my model (SHS5AV55UC/22) so all I have to go on as far as error codes is the blinking sanitized light. (Blinks nonstop)
 

if it does turn out to be the control board, that will be #4 in less than a year, which implies that there is something else that is causing the control boards to burn out.