SHV 4803 Bosh DW Water Valve Gremlins

[rnpatrick]

Guys - sorry for the long winded post, but this thing has me pulling my hair out

About 2 months ago the DW stopped filling - it would go through the whole cycle without running any water into the tank.

I discovered that if I pour about a gallon of water into the bottom of the tank, the DW uses that water for the pre-rinse, drains it, then the valve opens and the DW works normally. The problem was intermittent - maybe 1 out of every 5-10 wash cycles it would fail, I would pour in water and it would be fine for a while. I figured one of the water level switches was going bad but did not have a wiring diagram or time to look at it when it was failing.

About 1 month ago I found a wiring diagram and sat down with an ohm meter to troubleshoot what component was causing the failure. To my surprise, the water level switches all checked OK. What I did find was that the coil on the valve was open.

So I ordered a replacement water valve, installed it and everything has been working until today. Today it did not fill and I checked everything with the meter and the new valve's coil was open. So I poured water in the tank, started the cycle and sure enough, it all worked. Now the water valve coil reads about 1k ohms.

What is the likelyhood that I got a bad replacement water valve? ( I can see this is possible but unlikely)

More puzzling - what would cause the valve to start working just because I poured water into the tank? (I have no explanation for why this works.)

At this point, I am at a loss as to what could be the real failure. Any suggestions greatly appreciated.

Rob

[RegUS_PatOff]

... Now the water valve coil reads about 1k ohms...

that's what it's should read ...

could be a bad Timer ..
you'd have to check the voltage at the Water Valve ...

[Repair-man]

Mostly, I hear this when the float switch is clogged up on the left side of the unit. Grease and soap residues make for some pretty nasty buildup in the fill chambers, causing the erratic operation you describe. I suggest getting ahold of a Bosch D/W manual like the one below, to see how the float assembly works and how to service it. Lots of fun, as the unit will be pulled out and the left side of the cabinet removed.

Bosch Dishwasher Service Guide

When manual loads, click on the topic "Water fill assemblies"

[rnpatrick]

... Now the water valve coil reads about 1k ohms...

that's what it's should read ...

could be a bad Timer ..
you'd have to check the voltage at the Water Valve ...

I am thinking it is the control as well - I will check the voltage next time it fails.

Thanks for the help - much appreciated!

[rnpatrick]

Mostly, I hear this when the float switch is clogged up on the left side of the unit. Grease and soap residues make for some pretty nasty buildup in the fill chambers, causing the erratic operation you describe. I suggest getting ahold of a Bosch D/W manual like the one below, to see how the float assembly works and how to service it. Lots of fun, as the unit will be pulled out and the left side of the cabinet removed.

Bosch Dishwasher Service Guide

When manual loads, click on the topic "Water fill assemblies"

The float switches were the first thing I looked at - pulled the unit out, popped off the side and the switches were as clean as a whistle.

Plus I checked them with an ohmmeter and they all work - even when the problem occurs.

Thanks for the pointers - the troubleshooting will resume when it fails again