If your dishwasher is no longer draining properly, there's a very good chance the drain pump inside the machine has stopped working properly. However, it's always a good idea to make sure the part in question is indeed faulty before you attempt to replace it. Fortunately, multimeters are helpful tools that can be used to test certain appliance parts for faults, which is why we're here to show you how to use a multimeter to test the drain pump in your dishwasher and replace it if necessary.
For this guide, we are using a Bush slimline dishwasher. Please note that this process may differ slightly if you own a different make and model of dishwasher, but it should generally be the same. However, if you find you need to replace the drain pump but own a Smeg appliance instead, we have a guide showing you how to replace the drain pump on a Smeg dishwasher too.
If you follow this guide and find that it doesn't fix the problem, we also have an article on diagnosing dishwasher draining and motor problems to help you determine what else the problem might be.
What you will need
- Phillips screwdriver
- Drain hose unblocking tool
- Multimeter
- New drain pump (if faulty)
Finding your model number
If you find that you need to replace your dishwasher's drain pump, it's important to know your dishwasher's model number as this number will help you buy the correct replacement part for your particular appliance. Don't know what your dishwasher's model number is or how to find it? Don't worry! Our guide on how to find a dishwasher model number will get you in the know.
How to use a multimeter to test the drain pump in your dishwasher
Let's dive in! To learn how to test a dishwasher drain pump with a multimeter, either watch the video below or follow the written step-by-step guide beneath.
Safety first
Remember, always make sure your appliance is switched off and unplugged from the mains before carrying out any work. For this process, you will also need to turn the mains water supply off. Also, if the water feed hose going into your dishwasher isn't long enough for you to safely work on the machine, you'll need to disconnect that as well. If you disconnect this hose, remember to lay a towel down in case of any water spillages.
Step 1: Check the drain hose
Before disassembling your appliance to check the drain pump, it's a good idea to first make sure a blocked drain hose isn't to blame for your dishwasher not draining properly. To do this, work a drain hose unblocking tool inside the drain hose and check for any blockages, removing any you might find.
If you do find and remove any blockages, make sure you test your dishwasher before carrying on with the rest of this process. This is because unblocking the hose may have fixed the problem, meaning the drain pump is working fine and doesn't need checking at all.
Step 2: Access the drain pump
If you've checked the drain hose but the draining problem persists, then you'll need to test the drain pump. To do this, you'll first need to access it. Flip the machine upside down, taking care not to damage it as you do so, and remove the bottom panel. Start by unscrewing and removing the two rear feet...
Then unscrew the four screws that hold the bottom panel in place using your Phillips screwdriver.
With the screws removed, you can lift the bottom panel away and place it safely to one side.
Step 3: Remove and check the pump
With the bottom of the machine removed, you will be able to see the drain pump, as pictured below. You will need to remove it to check it and test it. Do this by unscrewing the two screws that keep the drain pump connected to its housing with your Phillips screwdriver (one screw at the top and one screw underneath). In larger dishwashers, you will be able to use a standard Phillips screwdriver. For slimline models, however, you may need to use a small Phillips screwdriver as there likely won't be much space to access these screws.
With the screws removed, you will be able to pull the drain pump free. However, the pump will still be connected to the dishwasher by its electrical connections, so you can go ahead and disconnect these too.
Before testing the drain pump with your multimeter, there are some other checks you'll need to carry out. First, check that the impeller can spin freely and that it isn't blocked. If blockage free, or when you've unblocked it, the impeller may turn in a jerky motion. This is normal due to how the magnet works.
Then check inside the drain pump housing as well, making sure there are no blockages and removing them if necessary.
Step 4: Test the drain pump with a multimeter
Now it's time to test your drain pump with a multimeter! To do this, set your multimeter to 200 ohms.
Then place the two multimeter probes onto the drain pump's tabs from which you removed the electrical connections. If your drain pump is working properly, the multimeter should show a reading of between 160 and 260. If the reading is too high, too low, or if there's no reading at all, it means the drain pump is faulty and needs to be replaced with a new one.
Step 5: Refit the drain pump
Now it's time to fit your new drain pump (or refit the old one if it was working fine). To refit the drain pump, slot it back onto the drain pump housing and twist it into position.
Then refit the two screws to secure the drain pump in place...
And reconnect the two electrical connections to the drain pump's tabs.
Step 6: Refit the bottom panel
Now you can refit the dishwasher's bottom panel. With the bottom panel in place, screw the two rear feet back in...
Then return the four screws to secure the bottom panel onto the bottom of the dishwasher.
With the dishwasher upright once more, you can reconnect the water supply hose and turn the mains water supply back on.
And there you have it! How to test a drain pump in a dishwasher with a multimeter. Your appliance should now be working properly once more!
Now that your dishwasher is in working order again, it's a good idea to make sure you're using it as efficiently as possible to save money and get the best cleaning results. Check out our guide on dishwasher energy saving tips to learn more!
Finally, don't forget to subscribe to our YouTube channel for plenty of appliance care videos, including step-by-step repair guides and handy appliance maintenance advice to keep your appliances running for longer.
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