My DeWalt Angle Grinder Stopped Working: How I Fixed It

It was a hot Saturday. I was in the yard. I was working on a metal gate for the garden. I had my DeWalt DWE402 angle grinder in my hand. I was cutting a piece of old iron.

Then, it stopped.

The tool just died. It did not smoke. It did not make a weird noise. It just quit mid-cut. I pulled the trigger again. Nothing happened.

I felt a knot in my stomach. I looked at the yellow tool. I thought my project was over. I almost threw it. But I took a deep breath. I wanted to fix it.

If your DeWalt angle grinder stopped working, do not panic. You likely do not need a new tool. For me, it was a cheap part. It was a ten-minute fix.

Here is what I learned.

Why Did It Stop?

I took the grinder to my bench. I like to solve puzzles. This was just another puzzle.

When a tool dies with no smoke, check three things:

1. The Carbon Brushes (The likely cause)
2. The Power Cord
3. The Switch

I looked up my model. I found a cool fact. Modern DeWalt tools have a safety feature. It is called “Auto-Cut” brushes.

The “Auto-Cut” Safety Pin

This was news to me. DeWalt makes the brushes fail on purpose.

It sounds bad. But it is smart. The brushes rub on the motor to give it power. If they get too short, the metal spring can hit the motor. That would ruin the tool.

So, they put a tiny pin inside the carbon brush. When the carbon gets low, the pin pops out. It pushes the brush back. The power cuts off. The tool stops. It saves the motor.

How I Found the Problem

I wanted to be sure. Here is the list I used.

Step 1: Check the Power

First, check the outlet. Is it working? I plugged a lamp into the cord. It turned on. The power was fine.

If you have a battery tool, check the charge. Put the battery on the charger. Make sure it is full.

Step 2: The “Wiggle” Test

Cords break often. They break right where the cord meets the handle. This spot twists a lot.

• I plugged the grinder in.
• I held the trigger down.
• I wiggled the cord hard at the base.

The Result: My grinder stayed dead. If it turned on for a second, the cord would be bad. Mine was silent. The cord was okay.

Step 3: Check the Brushes

This is where I found the issue.

On my DWE402, this is easy. You do not need to take the tool apart. Look for two round plastic caps near the back.

• I unplugged the tool. Always unplug it first.
• I used a big flat screwdriver.
• I unscrewed the cap.
• I pulled out the brush.

The Find: The carbon block was tiny. It was very short. A small pin stuck out of the face. This was it. The safety pin had done its job.

Quick Guide to Symptoms

I made this table to help you. Find your symptom to see the cause.

How I Fixed It

I knew the problem. Fixing it felt good.

I bought new brushes online. I searched for “DeWalt DWE402 replacement brushes.” They cost me about $12.

Here is how I put them in.

Tools I Used

• Flathead screwdriver
• Compressed air (optional)
• New carbon brushes

The Steps

1. Open the caps: I unscrewed the black caps on the sides.
2. Remove old brushes: The old ones popped right out.
3. Clean it out: I saw dust inside. I used air to blow it out. Dust is bad for the motor.
4. Put in new brushes: I pushed the new blocks in. Line up the metal “ears” with the slot. It should fit tight.
5. Close it up: I screwed the caps back on. Do not screw them too tight. You might crack the plastic.

The “Bedding In”

I plugged it in. I was nervous. I pushed the trigger.

It started up! But I smelled a burning scent. I saw a few sparks.

This is normal. New brushes need to fit the motor. This is called “bedding in.” I let the tool run for a minute. I did not cut anything. The smell went away. The sound got smooth.

What If It Was Not the Brushes?

If the brushes were fine, I would check the switch.

Grinders suck in air. They also suck in dust. Dust can clog the switch. This stops the power.

To fix that, I would have to open the handle.

1. Take out the screws on the handle.
2. Open the plastic shell.
3. Use a meter to check the switch.
4. If the switch does not work, buy a new one.

I was lucky. I did not have to do this.

How to Keep It Running

I want my tool to last. Here are tips I use now.

• Blow it out: After I cut stone or metal, I blow air into the vents. This keeps dust out of the switch.
• Do not press hard: I used to push on the tool. That is bad. It heats up the motor. Let the disc do the work.
• Check the grease: Once a year, I check the gear head. If the grease is dry, I add more.

Final Thoughts

It is a pain when a tool dies. It stops your work.

But do not toss it. Do not buy a new one yet.

For me, it was a $12 part. The fix took ten minutes. It felt great to hear that motor spin again. I finished my gate that day.

Next time your tool dies, stop. Unplug it. Check the brushes. You might save a lot of cash.

FAQs – DeWalt Angle Grinder Stopped Working