How to Test a Headlight Bulb with a Multimeter?

If you're experiencing issues with your vehicle's headlight bulb, such as dim or non-functioning light, it's important to determine whether the bulb itself is faulty. One way to do this is by testing the headlight bulb with a multimeter. A multimeter is a versatile tool that can measure voltage, resistance, and continuity. In this article, we will guide you through the process of testing a headlight bulb using a multimeter. Let's get started! 

Benefits of testing headlight bulb with the multimeter

There are a few benefits to testing headlight bulbs with a multimeter: 

  • It can save you time and money. If you can quickly and easily test a headlight bulb and determine that it is bad, you can avoid having to take your car to a mechanic or replace the bulb unnecessarily. 
  • It can help you diagnose other problems. If you test a headlight bulb and it passes, but your headlights are still not working, it can help you narrow down the problem to other components in the headlight circuit. 
  • It is a relatively easy and safe procedure. Testing a headlight bulb with a multimeter does not require any special skills or tools. You can do it yourself in your driveway in just a few minutes.


What You'll Need 

Before we begin, gather the following tools: 

  • Multimeter: Make sure you have a multimeter that is capable of measuring resistance (ohms) and voltage (volts). 
  • Safety Precautions: Wear safety glasses or goggles to protect your eyes from any potential hazards. 


How to Test a Headlight Bulb with a Multimeter?

Follow these steps to test your headlight bulb: 

  1. Safety First: Turn off the vehicle's engine and remove the key from the ignition. This will ensure your safety throughout the testing process. 
  2. Access the Headlight Bulb: Depending on your vehicle, you may need to open the hood or access the headlight assembly from the front of the vehicle. Consult your vehicle's owner's manual for specific instructions on accessing the headlight bulb. 
  3. Disconnect the Bulb: Locate the headlight bulb socket and gently disconnect it from the wiring harness. This will allow you to test the bulb separately. 
  4. Set the Multimeter: Set your multimeter to the resistance (ohms) mode. Refer to your multimeter's user manual if you're unsure how to do this. 
  5. Test the Filament: Touch the multimeter's probes to the two contacts on the headlight bulb's base where the wires were connected. The multimeter should display a resistance reading. A reading of infinite resistance (OL on the display) indicates a broken filament and a faulty bulb. A reading close to zero resistance indicates a good bulb. 
  6. Switch to Voltage Mode: If the resistance test indicates a good bulb, switch your multimeter to the voltage (volts) mode. 
  7. Connect the Bulb: Reconnect the headlight bulb to the wiring harness, ensuring a secure connection. 
  8. Activate the Headlights: Turn on the vehicle's headlights. 
  9. Test Voltage: With the headlights activated, touch the multimeter's probes to the two contacts on the headlight bulb's base. The multimeter should display a voltage reading. A reading close to the battery voltage (usually around 12 volts) indicates a proper electrical connection. 
  10. Repeat the Process: Repeat the resistance and voltage tests for the other headlight bulb if necessary. 


Testing headlight bulbs is a relatively simple procedure that can be done with a multimeter. If you are not comfortable doing it yourself, you can always take your car to a mechanic. However, testing your headlights yourself is a good way to save time and money, and it can help you keep your car safe on the road. 

Here are some of the signs that your headlight bulbs may need to be tested: 

  • Your headlights are dim. This is the most obvious sign that your headlight bulbs may need to be replaced. 
  • Your headlights are flickering. This can be caused by a loose connection, a bad bulb, or a problem with the headlight switch. 
  • One of your headlights is not working at all. This could be caused by a bad bulb, a blown fuse, or a wiring problem. 
  • Your headlights are not pointing in the correct direction. This can be caused by a problem with the headlight alignment, or it could be a sign that one of your headlight bulbs is not working properly. 


If you notice any of these signs, it is a good idea to test your headlight bulbs to see if they need to be replaced. 

For high-quality headlight bulbs and automotive lighting solutions, visit Underground Lighting. We offer a wide range of products to meet your lighting needs.