How Do You Test A Brake Pedal Position Sensor? (Explained)

There are plenty of different parts and components that allow the car’s entire brake system to work properly.

One such component is the brake pedal position sensor or switch, which basically toggles the brake lights on when you press on the pedal. So, how would you know if you have a bad brake pedal position sensor?

How would you know if you have a bad brake pedal position sensor or switch?

The best way to test a brake pedal position sensor is by using a multimeter that could get the voltage running through the sensor. Simply put the multimeter on the wires and then press the pedal down while the car is turned on. If the multimeter cannot pick up a voltage, the sensor is faulty or damaged.

You need to know that the brake pedal position sensor plays a very important role in the entire brake system because there are some cars that will not even function properly when the brake pedal sensor has gone bad.

As such, it is very important for you to know how to properly test a brake pedal position sensor to know if you need to have it fixed or replaced.

How do you know if your brake pedal position sensor is bad?

The brake system of a car is one of the most important systems that any vehicle has because of how it allows the car to properly come to a full stop when you press on the brake pedal.

However, the system also works in a way that allows everyone on the road to stay safe due to the brake lights found on a vehicle.

When the driver steps on the brake pedal, what happens is that a signal will be sent to the brake lights to turn them on. The lights will then indicate to the vehicle behind you that you are braking so that they can also brake or make a quick swerve to avoid a collision. Find out more on why brake lights only work when the pedal is pressed hard.

As such, this is one of the most important safety features of any vehicle. And the entire system works thanks to the brake pedal position sensor or the brake light switch.

The function of the brake pedal position sensor or brake light switch is to sense the position of the brake pedal. If the sensor or switch senses that you have pressed on the brakes, what it does is that it will now send a signal to the brake lights, which will now illuminate. The same sensor or switch also sends another signal to the car’s computer.

Brake pedal position sensors or brake light switches are so important that there are some cars that will not work well when the sensors or switches are damaged. For example, the transmission will lock at park, or the push start button will not even work when there is something wrong with the brake pedal position sensor or brake light switch.

In that regard, how would you know if the brake pedal position sensor has gone bad?

There are only a few indications that would point to the possibility that there is something wrong with the brake light position sensor. And all of them have to do with the brake lights and how they react.

The first indication of a bad break pedal position sensor is when the brake lights turn on, even when you are not pressing on the brake. Meanwhile, the opposite of that is when the brake lights will not even turn on when you are stepping on the brake. Of course, in some cases, you would have to step really hard on the brake pedal just so the brake lights will turn on.

In all of those cases, the easy conclusion that anyone can come up with is that there is a problem with the brake pedal position sensor or brake light switch.

And the next thing you need to do is to confirm your suspicion by testing the brake pedal position sensor.

How do you test a brake pedal position sensor?

Suppose you want to know if there is something wrong with the brake pedal position sensor, such as when it has become worn out, and in need of replacement, the only way for you to test whether or not it is working is by using a multimeter to test for any voltage that is running through the sensor.

Here is how you do it:

  • Search for the brake pedal position sensor or the brake light switch. This is usually found under the dashboard and just above the top of the brake pedal. The brake light switch will not be too difficult for you to spot.
  • Once you have found the brake light switch, what you need to do is to grab your multimeter. Depending on the car and the brake pedal position sensor that it has, there should be some wires that are found on the switch.
  • Turn the switch around 45 degrees to pull it out a bit. This will reveal the two wires that are attached to the switch.
  • Using your multimeter, what you need to do is to connect it to one of the wires found on the sensor while the car is turned on. Do the same with the other wire as well. The multimeter should be able to detect voltage running through the wires if the sensor is working properly.

If the multimeter was not able to detect any voltage running through any of the wires on the brake pedal position sensor, that means that there might be something wrong with the sensor.

In that case, what you need to do is to have the brake pedal position sensor replaced. Do not worry because having the brake light switch replaced is not that expensive.

How do you reset a brake pedal position sensor?

If the brake pedal position sensor is not faulty, but there are still problems with the brake light, then it could simply mean that you need to adjust the brake pedal position sensor by resetting it. And the way you reset it will depend on the issues regarding the brake pedal position sensor.

If your brake lights are turning on, even if you are not stepping on the brake pedal, what you may need to do is to press the brake pedal position sensor in place a bit by giving it a light nudge with a screwdriver.

Meanwhile, if the brake lights are not turning on when you are stepping on the brake, that means that you need to pull the sensor back in its proper place. To do so, try rotating it a bit. Maybe a 45-degree turn should allow you to pull the sensor back in place.

If the problems still persist even after you tried resetting the brake pedal position sensor, then you might want to have a mechanic check your car for any problems regarding the brake light switch. 

Sources

Your Mechanic: Brake pedal position switch replacement

efiautomotive.com: Brake pedal position sensor

RepairSmith.com: Brake Light Switch