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How to Diagnose Control and Programme Problems with a Dishwasher

In this video eSpares explain how to diagnose control and programme faults with a dishwasher, helping you keep your appliance working to its full potentail for longer.

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Video Transcript

Hi I'm Josh from eSpares, and in this video I'll be helping you to diagnose control and program issues with your dishwasher.

The first thing we’re going to look at is if your dishwasher is completely dead.

Safety First! Please make sure that you've switched off your appliance and disconnected it from the mains before beginning any repair.

The first thing to check is where the power is actually getting into the dishwasher, so unplug it from the socket and plug something else in such as a hair dryer or vacuum cleaner or anything, just to make sure that there is power at the socket.

Now once you've established that is the case we can move on to looking at the plug and making sure that the fuse in the plug hasn't blown.

I'm just going to take the back off the plug on the dishwasher, and then grab a multimeter place that onto the lowest resistance reading and just have a quick check of the resistance of the leads on your meter despite shorting them together and I'm getting a reading of about 1.7 ohms.

So if I just place the probes onto the fuse either end, I should get a similar reading if the fuse hasn't blown, and again I'm getting about 1.7 ohms so that shows that the fuse is OK.

Now when you've established that the fuse in the plug is OK, the next thing to do is check for continuity between the plug and the control board in the dishwasher. Now in this particular dishwasher the control board is housed at the top on the inside of the door, but it can vary from one model to another so in yours it may be at the bottom of the door or it may be on the side at the back of the dishwasher, so you may have to look around to find it.

I’m just going to start by unscrewing the screws around the inside the door so I can get to the control board inside. Okay so here we have the control board inside the door, now I’m looking for continuity between the plug and the control board so I'm going to be checking how the power comes down through the live and neutral pins on the plug, it’s then going to come possibly through an on off switch if your dishwasher has one, if it does make sure the switch is turned on for this and it then goes from the switch into the control board.

Now the way I'm going to be testing is by looking for a short circuit on the meter. Now of course normally a short-circuit is a bad thing, but in this case the short-circuit shows that there is a connection between the plug and the board. So I'm going to start by placing one of the probes of the meter onto the live pin of the plug, I'll just close the door to make it a bit easier, and then grab the other probe of the meter and place that onto the brown pin here and because I'm looking for a short-circuit it should read around about a couple of ohms, possibly less. Again I'm getting about 1.8, so now I’ve established the power is getting from the plug to the control board but not getting any further and that would probably explain why the dishwasher is dead and it's because the control board is faulty.

Now if when you do this you are getting the reading on the meter just try moving the probe on the board around all the different wires until you do get a reading, of course when you do get a reading that would show that the power is getting to the board, the board is faulty and may need to be replaced. On the other hand if moving the probe around still doesn't produce any reading then that would indicate that there is a fault between the plug and the board, and it’s most likely to be in the wiring.

The next fault we will have a look at is if your dishwasher is blowing the fuse when you turn it on. Now in most cases this is going to be caused by the presence of a short, and that can either be in the control board or in one of the components elsewhere in the dishwasher in most cases it's actually going to be in the heater.

Now we can test for a short just by using a meter to test across the live and neutral, or live and earth, pins on the plug, again a short is going to show up as less than a couple of ohms. Now if you do get the reading of a short circuit try disconnecting the heater and then testing again on the plug to see if the short is gone. If the reading is much higher, that would show the short-circuit is likely to lie in the heater. You can confirm that by testing the heater itself, for a working heater the reading should be somewhere between 20 and 50 ohms, so obviously any reading that is significantly outside of those would indicate that the heater has developed a short-circuit and you'll need to replace it.

Now let's move on to look at program problems and fault codes.

The control board in most dishwashers responds to faults in the appliance with a fault codes, and this can be through a combination of lights or letters and numbers. However manufacturers use different fault codes for their dishwashers, so it can be just as beneficial to watch the dishwasher and see when in a cycle it stops to determine when the fault is occurring.

The first point to which there might be a fault code is when you turn the dishwasher on. If water is leaked into it, the dishwasher may register this as a flood and you will hear the drain pump whirring continuously as it tries to get rid of that water. Now you can check to see if there's any sort of leakage by just tilting the dishwasher onto its side and watching to see if any water drains out the bottom. If it does, just take the base off the dishwasher and have a look inside at the pipes for any damage, it may also be that the detergent simply foamed too much and that has caused the leakage.

Whatever happens just get rid of any water or anything that is causing it to leak and then put the base back on and turn the dishwasher on again to see if that resolves the problem. Now when you turn your dishwasher on and closed the door to start the cycle the first thing that happens is the drain pump turns on, any liquids that run of the glassware or the crockery into the machine is drained away and that takes about 20 seconds. After that the inlet valve turns on and the dishwasher starts to fill with water until it's just below the door seal. Once it's hit the correct level and the wash pump turns on, and that's when you hear that familiar whoosh noise as the water is sprayed around the dishwasher, after that the heater turns on if required, and shortly after the heater turning on you'll hear that very familiar clunk noise as the dispenser drawer opens and lets the detergent into the dishwasher.

Now failure to complete any of those parts of the process will result in the dishwasher stopping and displaying a fault code. The rest of the wash cycle consists of washing draining and heating followed by the drying cycle. Now some dishwashers use a fan in the drying cycle to circulate air around the cavity and help the water evaporate of the crockery. While other dishwashers rely simply on the residual heat within the crockery for the water to evaporate off.

Now one final thing to consider if you need to replace the control board in your dishwasher, many manufacturers make their control boards so that they have to be programmed when they are fitted. Now this is possible for you to do, but it may require purchasing additional equipment and this can be expensive. So for that reason if you are replacing the control board you may prefer to use a fixed price repair service such as Repaircare who can do the fix for you.

If you need help with diagnosing other folks in the dishwasher see our other eSpares videos, and spares for dishwashers along with other appliances are available on the eSpares website.

Thanks for watching.

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