How to Test Brake Light Switch

Testing your brake light switch is important to ensure your safety and the safety of others while on the road. If your brake lights are not working, other drivers may be unable to tell when you’re about to slow down or stop, which can put everyone in danger. Fortunately, testing a brake light switch is fast and easy. All you need is a light tester and some basic instructions.

How to Test Brake Light Switch

Testing your brake light switch has several advantages. It allows you to diagnose any problems with your lights quickly and help prevent more serious issues from developing. Additionally, testing your brakes is a great way to ensure that all of your exterior lights function properly and that no bulbs have blown out. In this blog post, You will learn how to test brake light switch.

Tools You Will Need

  • Multimeter
  • Wire cutters or wire strippers
  • Phillips screwdriver
  • Electrical tape
  • Needle nose pliers
  • Flat head screwdriver
  • 10mm socket and ratchet wrench
  • Flashlight
  • Test light
  • Safety glasses or goggles

Step-by-step Instructions for How to Test Brake Light Switch

Step 1: Inspect the Brake Light Switch

Before beginning the testing process, inspecting the brake light switch for any physical damage or signs of corrosion is important. If you see anything unusual, replace the switch before further inspection.

Step 2: Disconnect the Negative Terminal from the Battery

Next, disconnect the negative terminal from your vehicle’s battery. This will ensure you are not shocked when performing the rest of the steps. Locate the brake light switch and disconnect it from its wiring harnesses. It is usually located on or near the brake pedal assembly. Depending on your vehicle, you may need to use a Phillips screwdriver to remove the screws holding it in place.

Disconnect the Negative Terminal

Step 3: Test for Power on Wiring Harness

Using a multimeter, test for power by placing one probe on the positive connection of the brake light switch wiring harness and the other on its negative connection. You may need to repair or replace the wiring harnesses if no power is present.

When the brake pedal is depressed, you should see voltage on a multimeter. To test this, place one probe on the positive connection of the wiring harness connected to the brake light switch and then move your other probe to each of the two wires coming from the brake pedal.

Step 4: Test the Resistance of the Brake Light Switch

Using a multimeter, measure the resistance of the brake light switch. You may need to replace it if it is greater than 6 ohms or less than 4 ohms. Check for any electrical shorts in the wiring harnesses and connectors using a test light or multimeter. Check each connection point individually if you find any issues, and repair or replace the affected parts as necessary.

Step 5: Test Switch with Key On/Off

Turn the key on and off several times while testing the switch. The lights should turn on and off with the ignition as expected. If this is not happening, the brake light switch may be faulty and must be replaced. Reconnect the negative terminal from your vehicle’s battery once you have finished testing.

Step 6: Test the Brake Light Switch Again

Once all of the above steps have been completed, testing the switch one final time is important. Make sure that the lights are operating properly and that they turn on and off with each press of the brake pedal.

Now that you know how to test a brake light switch, you can ensure that your brake lights are functioning properly and will remain on in the event of a sudden stop. In addition, proper testing also helps ensure your safety when driving at night or in inclement weather.

Tips for How to Test Brake Light Switch

necessary tools are on hand
  1. Always ensure the vehicle is not in gear, or it could cause significant damage and be dangerous to you and anyone around you.
  2. Ensure that all of the necessary tools are on hand before beginning testing—a multimeter, a test light, and a voltmeter will be handy for this job.
  3. Avoid working with live wires and turn off the power before beginning testing.
  4. Wear protective gloves when working with wiring or components to protect your hands from electrical shock.
  5. Ensure all connections are secure and tight before attempting to begin testing, as loose connections could lead to false readings or a malfunctioning brake light switch.
  6. If you are unfamiliar with how to test a brake light switch, then it is best to consult an auto mechanic for guidance and assistance. This will help ensure that the job gets done correctly and safely.

Testing the brake light switch involves inspecting the wiring and connections and conducting tests to confirm whether or not the switch is functioning correctly. To begin testing, disconnect the brake light switch from the vehicle wiring harness first.

What Are Some Common Signs of a Faulty Brake Light Switch?

If you’re experiencing issues with your brake lights, there are several common signs to look for that can indicate a faulty brake light switch. These include:

  • The brake lights do not turn on when the brakes are applied
  • One or both of the brake lights stay on even after releasing the pedal
  • The brake lights flash erratically while driving
  • A dim or completely nonfunctioning brake light

Various factors, including faulty wiring or a worn-out switch, can cause this issue. Testing the switch is an important part of troubleshooting and diagnosing the problem.

Are There Any Special Instructions for Testing a Brake Light Switch on Different Types of Vehicles?

Yes, some special instructions must be considered when testing a brake light switch for different vehicles. If you’re working on a traditional car or truck, the test should be done with the car in park and the parking brake engaged. You should then use an appropriate voltage tester to check both sides of the switch. If you’re working on an electric or hybrid vehicle, the instructions may vary as different models have specific guidelines for testing brake light switches.

Use an Appropriate Voltage Tester

When testing a brake light switch, make sure to check your vehicle’s wiring diagrams before beginning to correctly identify which wires are connected to each side of the switch. It is also important to note that the switch should only be activated when the brake pedal is pressed. It’s also important to note that it’s best to consult a professional mechanic if you encounter any issues while testing a brake light switch. This type of repair can be dangerous without the correct experience and knowledge.

How Can You Confirm That the New Brake Light Switch Is Working Properly After Installation?

After you have installed the new brake light switch, there are several steps you can take to confirm that it is working properly. The first step is to check for continuity through the switch using a multimeter. This process requires you to connect one lead from the meter to each of the wires connected to the switch and then measure voltage or resistance. If the voltage is higher or lower than expected, the switch may have an issue.

The next step is visually confirming that the brake lights turn on when pressuring the pedal. It could indicate a problem with the new switch or wiring if they do not. Finally, you can test for proper operation of your brake lights by using a 12-volt light bulb and jumper cable. This process requires you to connect one end of the cable to the battery’s positive terminal and the other end to each of the wires connected to the switch, then observe if the brake lights turn on when you press down on the brake pedal.

What Common Mistakes People Make When Testing or Replacing a Brake Light Switch?

When testing and replacing a brake light switch, people make a few common mistakes.

  • Not Checking the Operation of the Brake Pedal: You should check that your brake pedal is in good working order before replacing or testing the light switch. If not, replace it if necessary, as this can cause issues with your car’s brakes.
  • Not Testing the Brake Lights: Before replacing the switch, test your car’s brake lights to see if they work properly. If not, it could indicate a faulty switch, and you will know once you have tested it.
  • Installing the Wrong Type of Switch: Make sure you purchase the correct type of switch for your make and model of car. If you install the wrong one, it won’t work properly and could cause brake issues.
  • Not Cleaning the Connections: Ensure all the connections on the brake light switch are cleaned before installing a new one. This will ensure that the switch is working efficiently and correctly.
  • Ignoring the Electrical System: The electrical system in your car is an important part of its functionality, so check the wires and connections for any issues before installing a new brake light switch. If you notice any problems, it’s best to have them repaired or replaced before continuing.
Testing the Light Switch

Following these tips will help ensure that your brake light switch is tested and replaced correctly so your car is always safe to drive.


In conclusion, testing the brake light switch on your car is a relatively straightforward process. A basic understanding of how to test it can save you time and money in potentially costly repairs. With the help of this guide, hopefully, you have been able to determine if your brake light switch needs to be repaired or replaced.

Now that you know what is required for testing be sure to be prepared with the tools and supplies needed. Gather your multimeter, screwdriver, and other related materials before you begin. If in doubt about any of the steps outlined above, contact your local automotive expert for further assistance. Reading this post has helped you learn how to test brake light switch. Make sure the safety precautions are carried out in the order listed.

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