Have you ever been riding your eBike when the motor suddenly stops providing assistance—even though the battery is charged and the display is working normally?

If the throttle and pedal assist suddenly stop working, but the bike turns back to normal after releasing or adjusting the brake lever, the brake cutoff sensor may be the cause.

A brake cutoff sensor is designed to stop motor assistance whenever the brake lever is activated. This is an important safety feature, but if the sensor remains activated when you're not braking, it can prevent the motor from working normally.

In this guide, we'll explain how brake cutoff sensors work, what causes them to stay activated, and how to troubleshoot the problem.

What Is an eBike Brake Cutoff Sensor?

Many eBikes use a brake cutoff sensor to temporarily disable the motor when the rider applies the brakes.

When the brake lever is pulled:

Brake activated → Sensor sends signal → Controller cuts motor power

When the brake lever is released:

Brake released → Sensor returns to normal → Motor assistance resumes

This happens very quickly and is normally almost unnoticeable.

The problem occurs when the sensor incorrectly detects that the brake is still being applied.

Symptoms of a Brake Sensor Problem

A faulty or incorrectly adjusted brake cutoff sensor can cause several symptoms.

You may notice:

• Motor suddenly stops working
• Throttle does not respond
• PAS stops providing assistance
• Display remains on normally
• Battery still shows power
• Motor works intermittently
• Motor works after restarting the bike
• Motor stops after applying the brakes
• Error code may appear on some systems

One important clue is:

The display works normally, but the motor won't respond to either throttle or PAS.

This can indicate that the controller is receiving a brake cutoff signal.

Why Does the Brake Sensor Keep Cutting Motor Power?

Several issues can cause this problem.

1. Brake Lever Is Not Fully Returning

The simplest possibility is that the brake lever isn't returning completely to its normal position.

Check whether:

• The lever moves freely
• The lever returns completely
• Nothing is blocking the lever
• The brake cable or hydraulic system is functioning normally

Even a small amount of brake lever movement can potentially activate the cutoff sensor.

2. Brake Sensor Is Misaligned

Some brake cutoff systems use a sensor positioned near the brake lever.

If the sensor or magnet moves out of position, it may incorrectly detect that the brake is being activated.

Check whether:

• The sensor has moved
• The sensor position has changed
• The sensor and magnet are properly aligned
• Any mounting hardware is loose

3. Loose or Damaged Brake Sensor Cable

The brake cutoff sensor connects to the controller through an electrical cable.

Inspect the cable for:

• Loose connectors
• Damaged insulation
• Pinched wires
• Bent pins
• Water or dirt inside the connector

A damaged or unstable connection can cause intermittent motor cutoff.

4. Brake Sensor Itself May Be Faulty

If the brake lever moves normally and the cable looks fine, the sensor itself may be malfunctioning.

A faulty sensor can continuously send a brake signal to the controller, even when the rider isn't braking.

5. Wiring or Controller Issue

If both brake sensors appear to be functioning normally but the motor remains disabled, the issue may be further down the electrical system.

Possible causes include:

• Damaged wiring
• Controller connector problem
• Controller input issue

At this stage, further testing may be necessary.

How to Troubleshoot an eBike Brake Sensor

Step 1: Release Both Brake Levers

Make sure both brake levers are completely released.

Try gently moving each lever and confirm that it returns to its normal position.

If one lever feels unusually tight, loose, or doesn't return completely, inspect the brake system before continuing.

Step 2: Check Whether Throttle and PAS Are Both Disabled

This is a useful diagnostic clue.

Throttle and PAS both don't work

The brake cutoff system may be one possible cause.

Throttle works but PAS doesn't

The problem is more likely related to the PAS system or its sensor.

PAS works but throttle doesn't

Check the throttle and its connection.

This simple comparison can help narrow down the problem.

Step 3: Inspect the Brake Sensor Connections

Turn off the eBike before inspecting electrical connectors.

If your model uses separate brake cutoff connectors, check whether they are:

• Fully connected
• Properly aligned
• Free from visible damage
• Free from water or debris

Do not pull on the wires when disconnecting a connector.

Step 4: Check the Sensor Position

If your brake system uses a magnetic or lever-mounted sensor, check its position.

The sensor should remain securely mounted and correctly aligned according to the manufacturer's design.

A sensor that has shifted after transportation, maintenance, or an impact may incorrectly detect brake activation.

Step 5: Perform a Diagnostic Test

If the problem continues, a qualified technician can temporarily disconnect the brake cutoff sensor for diagnostic testing.

Important: This should only be used as a troubleshooting step. The brake cutoff function is a safety feature, so it should not be permanently bypassed or disabled.

If the motor starts working normally after the sensor is disconnected, this provides strong evidence that the brake cutoff system is involved.

After testing, reconnect or replace the faulty component as appropriate.

Why Does the Motor Work Again After Restarting?

Some riders notice that the motor works normally after turning the eBike off and back on.

This doesn't necessarily mean the problem is fixed.

A restart can temporarily reset the controller, but if the brake sensor continues sending an incorrect signal, the motor may stop again.

If the problem repeatedly returns after braking, bumps, or moving the brake lever, inspect the brake cutoff system rather than repeatedly restarting the bike.

What If the Brake Sensor Isn't the Problem?

If checking the brake system doesn't solve the issue, other components may need to be inspected.

Possible causes include:

• Throttle failure
• PAS sensor problem
• Controller issue
• Motor connection problem
• Battery connection problem
• Display communication issue
• Damaged wiring

This is why it's important to diagnose the symptoms instead of immediately replacing the brake sensor.

When Should You Stop Riding?

Stop riding and have the bike inspected if you notice:

• Brake lever does not return properly
• Brakes aren't working correctly
• Damaged brake cables
• Exposed electrical wires
• Burned or melted connectors
• Unusual electrical smell
• Motor behaves unpredictably

Brake problems should always be treated as a safety issue.

If the mechanical braking system itself isn't working correctly, don't continue riding just because the motor still operates.

How to Prevent Brake Sensor Problems

A few simple checks can help prevent intermittent issues.

Check Brake Levers Regularly

Make sure both levers move smoothly and return completely.

Inspect Cables After Transportation

Bike transportation and repeated folding/unfolding can move or stress cables and connectors.

Keep Electrical Connections Dry

Avoid directing high-pressure water at brake sensor connectors or other electrical components.

Don't Pull on Sensor Wires

Always disconnect connectors by holding the connector housing rather than pulling the cable.

Before Contacting eBike Support

If you still have the problem, provide:

• eBike model
• Which brake lever may be involved
• Whether throttle works
• Whether PAS works
• Whether the display stays on
• When the motor cuts out
• Any error code
• Photos of the brake sensor and connector
• A short video showing the problem

For example:

“The display stays on, but both throttle and PAS stop working after I use the right brake.”

This gives technical support much more useful information than simply saying:

“The motor stopped.”

eBike Brake Sensor Troubleshooting Checklist

Before replacing parts, check:

✓ Both brake levers return completely

✓ Brake sensors are properly positioned

✓ Sensor connectors are secure

✓ Wires aren't damaged or pinched

✓ Throttle operation

✓ PAS operation

✓ Display remains powered

✓ No damaged or burned connectors

If the problem continues after these checks, professional diagnosis may be required.

Final Thoughts

The brake cutoff sensor is an important safety feature designed to stop motor assistance when you apply the brakes.

However, a misaligned sensor, damaged cable, loose connector, or faulty sensor can sometimes make the controller think that the brakes are still being applied.

If your eBike display stays on but both the throttle and PAS stop working, the brake cutoff system is one of the components worth checking.

Before replacing the controller or motor, take the time to identify the actual cause.

And if you're riding a Revi eBike, providing your model, photos of the brake sensor connections, and a short video of the problem can help the support team diagnose the issue more efficiently.

Frequently Asked Questions

Why does my eBike motor cut out when I use the brakes?

That's normal behavior. The brake cutoff sensor is designed to temporarily disable motor assistance when the brake lever is activated.

Why won't my eBike motor work after releasing the brake?

If the motor remains disabled after releasing the brake, the brake cutoff sensor may still be sending a brake signal. Check the lever, sensor position, cable, and connector.

Can a brake sensor stop both throttle and PAS?

Yes. If the controller receives a continuous brake cutoff signal, it may disable motor assistance from both the throttle and pedal assist.

How do I know if my brake sensor is faulty?

If the brake levers return normally but the motor remains disabled, a technician can perform a diagnostic test by temporarily disconnecting the brake cutoff sensor. If motor assistance returns, the sensor or its wiring may be involved.

Should I permanently disconnect my eBike brake sensor?

No. The brake cutoff system is a safety feature and should not be permanently bypassed. If the sensor is faulty, it should be properly repaired or replaced.