Bosch Dishwasher model SMS40T42UK/34 Check Water light flashing

[npyfs]

Cannot find an answer elsewhere so hope someone can help with this.
Bosch sms40t42uk/34 2014 mfr, but used very little.

I press ‘on’ button, machine does self check – lights
flash a bit – all turn off, but check water light begins to flash
continuously along with drain pump humming/emptying. If I pour water
into machine, it empties fine. Checked for blockages – none. Have
replaced drain pump and flood switch – no errors found on the original
ones – and have confirmed no evidence of water ever having been in flood
tray – polystyrene float as clean and dry as the day it was put in. No
water in bottom of case at all. Have removed matrix and swilled out the
very small amount of crud in there. Flow meter spinning freely.

Everything I read says a flashing light indicates a drain/flood problem.
Pressed start/reset button for 10 seconds – does nothing – flashing ‘check
water’ light stays on. If I press on/off button, after a few seconds
machine powers down and lights go off. Switch on again and the whole
problem described above repeats. Have had this machine stripped down –
tilted it 90 degrees to sides, front and back. It has no leaks, it
hasn’t flooded, filters clean as new, pipes into and from machine flow
freely.
Are there any other reasons for a flashing ‘check water’ light?

[electrofix]

if you check your owners manual it will say solid check water light is a water fill or drain problem but when it flashes it can be any other fault

and no easy way of telling which one

dave

[npyfs]

Thanks for your reply. Given the info I have included, any suggestions as to where to look first? The only thing I can think of is the inlet solenoid, but why would the machine be trying to pump as soon as it is turned on?

[electrofix]

if it was inlet solenoid the light would not flash

think I would open the timer and check for blown components

Dave

[npyfs]

Thanks Dave. Have checked clock / PCB by eye (magnifying glass) and no obvious sign of burnout/arcing or electrical failure. Any other suggestions of common faults?

[electrofix]

if the pump is running all the time have a careful look at the triacs. l plus check for short circuited ones. you need to identify the one for the pump

Dave

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