dewalt lawn mower wont start

Dewalt Mower Won’t Start (SOLVED)

Dewalt makes a range of tools for the home and garden and this is a coveted brand. Compared to some others, Dewalt lawn mowers are considerably high end and extremely reliable. But of course, there is always room for improvement and you may find yourself at a loss and wondering why your Dewalt lawn mower won’t start.

There could be a number of issues causing this problem but the most common is that the battery is faulty or dead. Other things that can affect how easily your Dewalt mower starts could be broken internal components or simply not having the mower set up correctly.

But don’t worry, with our checklist, you’ll be able to troubleshoot and have your Dewalt mower up and running again in no time.

1. Damaged Or Faulty Battery

Your Dewalt lawn mower may run on a battery and if this isn’t in tip top condition then you’re going to have problems with your mower getting started.

However, you may sometimes find that the battery simply doesn’t have enough juice left to get going. Properly charging your battery will ensure that you always have enough power to mow the entire lawn.

Your Dewalt lawn mower won’t start if its battery is not correctly inserted. The battery must be placed properly into the mower in order for it to make the connections.

Over time, your battery will lose its ability to hold charge. This is totally normal and something you’ll need to be prepared to deal with when owning battery powered tools. The more you charge it, the more wear this puts on the battery and eventually it will need to be replaced.

How To Fix It

Check that the battery is correctly installed in the lawn mower. If it is, check whether it is charged. If not, plug it in and allow it to fully charge before trying again.

If you still have problems then it could be that the battery is faulty. If you have other Dewalt tools, you may be able to take the batteries from those and use them in your lawn mower. For example, if you have a Dewalt 40v mower, any of the 40v batteries from the brand will work. That said, you’ll still want to replace your dodgy battery.

Note that if your mower is brand new out of the box with a brand new battery that doesn’t work, you will be covered by a warranty to have this replaced.

2. The Circuit Breaker May Have Tripped

A circuit breaker is a safety feature that cuts off power should there be a surge. If your Dewalt lawn mower won’t start then it could be that the circuit breaker has tripped.

Your lawn mower demands quite a lot of power and this could cause a circuit breaker to trip if it is overloaded. This is normally the case when using an extension cable. You’ll know that this is a problem because normally, your mower will initially fire up but shuts off shortly after.

To properly identify the problem, you might plug in a small appliance that doesn’t demand as much power. This could be something like a radio or a lamp. If this works then it’s likely the lawn mower that’s causing the circuit to trip.

How To Fix It

If you are using an extension cable, you must make sure that this is compatible with your lawn mower. Check the power demands of the mower and compare these to the capacity of the extension lead. If it exceeds the recommended voltage then you’ll need to switch to something that can handle it.

3. Broken Start Switch

The problem could lie with your start switch but, before checking this, we would recommend having a look at the connections first. In addition to this, it’s a good idea to make sure that the mower vents are not clogged with debris before you go messing around the starter switch.

Once you are confident that there aren’t any related problems, you can check the starter switch to see if it is functioning as it should.

dewalt mower start switch

How To Fix It

If the start switch is the issue then you will need to have this replaced. Unfortunately, this isn’t as simple as some other mower part replacements so you’ll probably need to take it to a professional. That said, some people can manage this quite well.

In most cases, a new start switch will sort the problem but if it doesn’t then you might need to have the mower checked by a technician.

4. Damaged Fuse

Your Dewalt lawn mower has a fuse key whose job it is to complete the electrical circuit. However, sometimes this can become damaged and that means that the lawn mower won’t turn on.

How To Fix It

In this case, you will need to replace the fuse which is a simple fix that can be done at home. However, if you are in any doubt about how to do this, hiring the help of a professional is the best idea.

5. Dewalt Key Is Not Fully Engaged

A lot of lawn mowers come with a key which has to be properly engaged in order for the machine to start. These keys are designed to prevent the lawn mower from starting up when it is not meant to; for example, during maintenance or by a child.

It might seem like quite an obvious thing when you think about it but when you’re rushing around trying to get garden jobs done, it’s all too easy to not insert the key properly and then you’ll never get anywhere.

When the key isn’t correctly inserted, the lawn mower won’t start. What’s more, it could be that the key looks as though it’s properly inserted but, when you try to turn it, nothing happens and there is resistance.

dewaly mower safety key

How To Fix It

Thankfully this is one of the easiest fixes for a Dewalt lawn mower that won’t start. All you need to do is take the key out and reinsert it correctly.

It is worth taking the time to read your user manual when you purchase your lawn mower as this will familiarize you with all of the components and prevent simple issues from arising in the future.

6. Bad Sensors

Sometimes the sensors on your electric lawn mower can go bad and this will affect how well the machine starts.

If you Google this problem, then you will see that there are a lot of remedial videos giving you instructions on how to fix this problem.

How To Fix It

If you are able to use a soldering iron, then it is possible to bypass the sensors so your lawn mower doesn’t have issues getting started. However, this type of work could void your warranty so it’s worth considering whether you’re happy to do this or not before you start.

The benefit is that, if you are able to perform the job, it’ll take much less time than claiming a repair or replacement on your warranty so you won’t need to wait to mow the lawn again.

7. Plug-Ins Aren’t Connected Properly

Inside your lawn mower, there is a network of wires and cables that distribute power and make connections. However, it is possible for these plug-ins to come loose from time to time and when a connection is lost, this makes it difficult to get the mower running.

How To Fix It

You will need to take a look inside your lawn mower to make sure that there are no disconnected or loose plug-ins. If you have a battery powered Dewalt lawn mower then taking a good look around the battery is a good place to start as this is where connections often come loose.

If you notice anything disconnected or simply not connected properly then adjust this and tighten things where necessary. In some cases, it might be the most minor adjustment that gets your mower up and running again.

8. The Vents Are Clogged

Your electric or battery powered Dewalt lawn mower has air vents that allow good circulation around the inside of the machine. However, as you use your mower, these vents will naturally become clogged with debris and grass clippings.

If these are not removed, no air can flow and this may cause the lawn mower to overheat. As a safety function, your Dewalt mower won’t start when the vents are clogged.

dewalt mower vent

How To Fix It

Check your vents and remove any clippings or debris. Try restarting your mower and this should have solved the problem.

9. Damaged Outlet

Earlier, we talked about power problems associated with using the wrong power outlet. However, while this may sometimes be an issue, it could also be that the power outlet is damaged and therefore, not functioning correctly.

When the outlet is damaged, it won’t deliver enough power and your dewalt mower won’t start.

How To Fix It

Check your power outlet using another appliance. If this also doesn’t work, it’s a good indication that there is an issue with the socket.

It’s imperative never to attempt electrical work so, in this instance, we would recommend hiring the services of a professional sparky. In the meantime, you can switch to an alternative power outlet to use your lawn mower.

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Andrew Fisher

Andrew Fisher

Andrew is a dedicated father of three who really takes pride in his lawn and garden. You'll find Andrew behind the scenes of almost everything Edge Your Lawn produces. When he's not helping readers find all the information they need, he's in his backyard working on his lawn and garden landscaping. This year he hopes to build an outdoor deck and sort out his veg patches.