Dishwasher electrical conundrum

[stu]

Colston 700S countertop dishwasher, made in Sweden c. 15 years old, sticking on rinse cycle. I dismantled the programmer and cleaned the contacts and re-assembled. Now it's not turning off the second solenoid tap which fills for the main wash cycle, so it floods. The diaphragm water-level sensing switch works ok for the first solenoid tap on the pre-wash, so its not that. The programmer is a series of cam operated rocker switches. The first rocks one way to fill for the pre-wash and the other way for the main wash. All connections are making ok. Any idea what could be going wrong? Stu.

[Paul]

had a problem similar to this with my dishwasher...... different make and model though

turned out it was the main pump that had broke, the impellor was broken from the motor shaft and it still pumped water because the impellor would turn a small ammount but not strong enough. The dishwasher has a 'dirt' sensor and just kept sticking on the wash cycle because it never registered as being clean. I know this is not like your problem but I went through a similar fault finding excersise and didn't check the pump because the symptoms led me to check other things.

Sorry I couldn't help more Paul

[BigWallop]

The wiring sounds wrong somewhere. The water level sensor has two switches inside which will turn on / off at the set water level. The first, shallow, level is working OK, but the second, deeper, level isn't working.

Check that the diaphragm switch isn't faulty first by blowing up the tube from the bottom. Blowing gently should activate the first switch. Blowing a bit harder should activate the second switch. You should hear them both operate as you blow.

Check the switch on the timer unit to make sure it's working OK. Putting a meter or a lamp over the switch and operating it will tell you if it is fine.

Check your rewire. Make sure you have the water level diaphragm switches on the correct parts of the timer unit.

[stu]

Tried that. 3 terminals on the switch, the click disconnects one and connects the other to/from the third. It works as it should for the primary fill, which is to the same level as the main wash fill. The programmer clock motor is odd. 2 wires connect it, both on the negative side of the mains, and when the programmer connects one of them (on the same block as the errant solenoid tap), the clock stops. Logical, because it will need to wait until it's full and it doesn't know how long that may be, but when it is disconnected the clock motor re-starts. How can it run with only one wire connected? Stu

[BigWallop]

It sounds as though you have the three wires to the water level switch in the wrong places then. There must be a common supply that operates between the two switches. These can either break the neutral side of the supply, or the live side. There must be a common supply wire to the switch. Have you tried tracing where these wires go to on the timer unit? One will either be connected permanently on the live or neutral supply to bring the timer motor back to life after the correct water level is reached. So it sounds like a wrong wiring configuration on the pressure detector.

Try swapping them around. It won't do any harm because they all connect together anyway, somewhere else.

[stu]

Don't think so, I was careful to mark them and replace as found. The common is permanently connected to the neutral side. One disconnects this from the misbehaving solenoid tap when the fill level is reached and in the same action the other connects to the emptying pump via some sort of resistor thingy that looks like a watch battery. But it continues to fill. :-(

[BigWallop]

Have a chat with the guys at

to see if they can get you through this conundrum, Stu. I don't have the proper diagrams for these machines any more, but the guys at UK Whitegoods should keep them all at hand.