Symptoms Of A Faulty Brake Light Switch

Here’re the signs that call for a brake light switch replacement: 

1. Brake Lights Won’t Turn On

When you hit your brake pedal, your car’s brake lights should turn on. But, if a brake light bulb has burnt out or there’s a faulty brake light switch, the light won’t illuminate. 

Without the brake light, the vehicle behind you won’t know that you’re slowing down. This can be a major safety hazard. 

2. Brake Lights Stuck On

Sometimes, your brake light might not turn off, even when you’ve removed your foot from the brake pedal. The chances are that there’s a short circuit in the light switch.

With the brake light stuck on, the driver behind you will get confused, thinking that you intend to slow down, even when you’re accelerating. 

Moreover, if your brake light stays on for long, it can damage the brake lamp and blow up the brake light fuse in the fuse box. 

3. Dead Battery

You may sometimes fail to notice that your brake lamp is stuck on, especially during the day. 

When that happens, it can slowly drain out your battery completely. You’ll not be able to use any electrical components, and your car won’t start.

You should get your brake light and switch inspected to rule out the cause of the battery drain. 

4. Car Won’t Turn On Or Shift Out Of Park

Some cars offer keyless ignition, where you need to press down on the brake pedal to start the vehicle. Similarly, in cars with automatic transmission, you need to press the brake to shift the gear selector out of Park. 

However, when your vehicle has a faulty brake light switch, you’ll not be able to do either.

Why? 

The brake switch is responsible for sending a signal to your car’s computer that the brake is engaged. When it’s not functioning, pressing the ignition switch won’t turn on your car, and you won’t be able to shift the gear. 

5. Bad Cruise Control

If your vehicle supports cruise control, a defective brake light switch can deactivate the system.

How? 

Your cruise control and the rear brake light may share the same switch. So, when the brake light switch fails, cruise control comes to a halt too.

However, the cruise control may also stop working due to a damaged speed sensor or a blown fuse in the ECM.

If you’re experiencing trouble with your cruise control, have your mechanic inspect the brake light switch as well. 

6. ABS Warning Light Turns On

When the ABS (Anti-lock Braking System) warning light of your vehicle comes on, it could indicate:

• A faulty ABS control module
• Low brake fluid
• A faulty brake pedal switch

The brake light switch signals the ABS module that the brakes are engaged, and it should start the hydraulic pump. So, if the ABS warning light (Check Engine light) is illuminated, it may be due to a defective brake switch. 

How Much Does Brake Light Switch Replacement Cost?

Unlike any other significant car repair, like the master cylinder or brake line, replacing a light switch doesn’t cost much.

You can be charged anywhere between $60 and $250, including labor costs. 

However, this cost could vary depending on:

• Make and model of the vehicle
• Brake light warranty offered by the auto parts store
• Switch series
• Recommended switch brand
• Labor charges in your location

How Urgent Is A Brake Light Switch Replacement?

If you own an automotive with a push-button start, and you happen to have a bad switch, your car won’t start.

In that case, you’ll need to get the faulty light switch replaced with a new switch at the earliest.

If your brake light is stuck on or off, you’ll still need to replace the brake light switch soon as it’s also illegal to drive a car with faulty brake lights. You may get ticketed for it and end up paying a hefty fine.

However, you can easily get your brake light switch tested and replaced by a mobile mechanic or at your nearest auto repair shop.

Brake Light Switch FAQ

Here’re answers to some common brake light switch questions: 

1. What Is A Brake Light Switch?

A brake light switch (also known as a stop light switch or brake lamp switch) is a spring-loaded electrical component responsible for turning your brake lights on and off.

How does it work?

Your car’s brake lights (tail lights) need a power connection from the car battery to work. The brake light switch controls this current flow when you engage the brake lever.

When you push the brake lever (brake pedal arm), a switch plunger (under the steering wheel) moves along the pedal and closes the light switch circuit. The current flows and the brake light illuminates.

Likewise, the switch plunger depresses when you release the pedal, the circuit breaks, and the lights turn off. 

In many modern cars, the stoplight switch also:

• Enables a push-button start
• Allows gear selector shift in automatic transmission 
• Influences ABS and Vehicle Stability Control 

2. How Often Should I Replace The Light Switch?

Unlike a brake pad, you expect a light switch to last longer. However, this switch is also prone to wear and tear, as it utilizes a mechanical switch plunger.

Since the switch body is close to a driver’s feet, it can come in contact with dust, dirt, or water, causing the switch to malfunction. This may also lead to a blown brake light fuse.

The chances of light switch failure further increase in stop-and-go traffic since the brake lights are constantly engaged.

As the stoplight switch is a critical component of your brake pedal assembly, it’s recommended to replace it as soon as possible. 

3. How Do I Replace A Brake Light Switch?

While it’s possible to replace a bad old switch as a DIY, it isn’t recommended. 

A faulty replacement can compromise your road safety.

Instead, you could take your car to a car repair shop or request a mobile mechanic to install the replacement switch right in your driveway.

Before replacing a stop light switch, they may use a multimeter first for testing and troubleshooting the voltage at the electrical connector when the brake pedal is pressed and released. A car’s service manual may also recommend testing the switch continuity when the pedal is depressed and released.

If the issue is a faulty switch, they can quickly replace it with a new one.

Here’s how a mechanic will replace a bad switch:

• Stop your car on a level platform and engage the parking brake.

• Disconnect the wiring harness of your car’s battery.

• • Reach under the steering wheel, where the pedals connect.

• Use a screwdriver to remove the Phillips head screws behind the brake pedal holding the electrical cover in place.

• Remove the panel covering the brake pedal assembly and access the defective brake light switch.

• • An older style faulty switch will require a socket wrench to remove the bolts holding the switch body to the metal bracket. For a newer style, they’ll have to rotate the bad brake light switch clockwise and pull it out of the socket.

• Next, disconnect and remove the wiring connector from the old switch.

• Install the new brake light switch and align it with the brake pedal arm. They’ll have to rotate the new switch clockwise to lock it in place.

• Reattach the panel to cover the brake pedal switch.

• Reconnect the wire harness of your car battery.

• Test and confirm that the new brake light switch and the other connected components are working as expected.