Five Signs That Your Brake Light Switch Is Not Working (& How to Replace It)

A vehicle's brakes must be in good working order. It is important to change the brake pads and check that everything works properly. The system switches and sensors are not under your control so people have to be aware of the warning signs that could indicate a defective brake light switch.

Part of the pedal assembly is the brake pedal switch. It alerts you when your vehicle needs to stop or slow down. If it's defective it can lead to problems starting the car or malfunctioning with the brake lights.

This will help you to identify a problem with your brake light switch so that it can be repaired and re-installed for working brake lights. We will discuss the symptoms and how to check the brake light switch. 

Bad Brake Light Switch Signs

1. Car Won’t Start

In the traditional keyed ignition, having a bad brake light switch won’t affect the ability to start the car. If you have a push-button starter, however, it could be a problem.

To start the engine you will need to press the brake pedal. If the system doesn’t recognize that you are pushing on the pedal, it’s not going to start. 

It is also true for many models of cars with automatic transmissions.

RELATED: Car Won’t Start? (10 Reasons & How to Fix it)

2. Keep Brake Lights On

A defective brake light switch can cause the brake lights to remain lit even when you shut the car off. It is due to a short in the circuit that causes the system's perception that you continue pressing down on the brake pedal.

You don’t ever want to let this situation go. This will wear down the brake lights and cause a parasitic charge on your battery. 

RELATED: Do Brake Lights Always Stay On? (5 Causes & How to Fix it)

3. Brake Lights Won’t Come On

A bad brake light switch could cause your lights to go out. If it’s not functioning at all, you may still want to look at this vital part. 

If the switch isn’t reading your movement on the pedal, the lights aren’t going to come on. This poses an on-road danger when other drivers don’t know if you are braking. 

4. Gear Selector Can’t Be Moved

The gear selector must be in Park. To do this, your brake pedal should be on. If the system isn’t reading your command, you may not be able to move the shifter into another position.

This situation leaves you stuck where you are. You can return to the road if you replace the switch in the spot you're at. 

5. LED Dashboard Warning Lights

The brake light switch can be a component of multiple systems so it's possible for several dashboard lights to come on if it fails. Common lights include the ABS (or Traction Control)

However, it’s also possible to see the Check Engine Light. The Check Engine Light is usually only activated if the brake pedal fails to work properly. It is important to check any lights that are illuminated immediately. 

Brake Light Switch

You will find the brake pedal assembly housing the brake light switch. It is located underneath the dashboard or firewall. It is found at the pedal lever’s top. It is easily accessible, which makes it easy to replace. 

In vehicles, the mechanical brake light sensor has been in use since 1960. Before that time, the switch was controlled by hydraulic pressure in the lines. This was dangerous and could quickly fail. 

In modern times, the brake light switch doesn’t commonly fail. A relay is now used in the modern design. The low-voltage circuit operates the main power switch for the car’s brake lights. This layout ensures that reliable switching is possible and the circuit has a long lifespan. 

Many functions are performed by the brake light switch. It’s needed to release your automatic transmission vehicle shifter out of Park. In push-button start systems, it’s also required to get the engine going. This switch is used to turn on or off your brake lights at the rear by reading the location of the pedal. 

How to test a bad brake light switch

Because of the handy location of the brake light switch, it’s not difficult to diagnose or replace. You can use a multimeter to test it and you won’t need to remove it for diagnostics. 

You should always start by reading your vehicle’s service manual, especially since the procedure can be performed in two different ways. Some vehicles will require you to check the voltage by depressing the pedal and releasing it. Some car models may require you to test the continuity of the switch by pushing and releasing the pedal. 

If you aren’t getting voltage to the brake light switch, the problem may just be a blown fuse. This problem is easy to fix once the fuse has been replaced. 

It is possible that you have two switches in your vehicle. If this is the case, both switches will need to be tested. You should refer to the service manual for details. 

Brake Light Switch Repair Cost

A brake light switch replacement can cost you between $75-350. Parts can cost $25-100, and labor in a professional shop could run $50-250. The prices will depend on which vehicle you have and what the rates at your local shop are. 

However, it’s not hard to replace the brake light switch at home, thereby saving you money on the labor. You should take between five and a half to two hours depending on where the brake light switch is located. 

There are some switches that are difficult to find, but most of them are in accessible locations. You might have to get rid of other components in order to reach the switch. It can make it difficult to finish the task. 

A bad brake light switch should be replaced immediately. If it’s causing the brake lights to stay on, you will drain the battery and reduce its lifespan. If the brake lights don’t come on at all, you are putting yourself in danger on the road. Additionally, you could be stuck if you can’t shift the gear selector or use the push-button start system. 

It makes perfect sense to have this service done at the first signs of trouble due to the cost. Considering the switch should last the lifetime of the vehicle, it’s unlikely you will have to perform the same service again.