Skip the auto shop - Our mechanics make house calls

Q: Are High and Low Beams Separate Bulbs?

asked by on

Are high and low beams separate bulbs?

A: This is a great question since depending on...

This is a great question since depending on the vehicle and manufacturer the lights can be configured in different ways. This can be a concern if you find your headlights are not working, since you need to know what type of bulbs to but to replace them with properly. Since the lens in modern headlights is separate from the bulbs this present a problem when replacing a lens for damage such as discoloration or from an impact.

Cars are built using single or dual filament bulbs. Older cars with single lights had dual filament bulbs that housed both the low beam and high beam light elements in a single bulb housing. These vehicles had two headlights total on the front one on each side. Then the design moved to individual bulbs which were single filament elements with a specific purpose of either a low or high beam light. These bulbs were arranged four total to the front of the car and configured either side by side on one on top of the other. The element in these bulbs work in a similar fashion to a household incandescent bulb. You may be even wondering how headlights work in general.

The adjust of the main beam of light from each of these light types is aimed or directed at different angles to improve the distance and angle of light beam reflected onto the road ahead of a vehicle. If the vehicle has a single headlight bulb (not the lens or reflector, but the actual bulb) then the bulb will have a dual filament internally which, when provided with battery power, will cause electrical current to flow through the element similar to the heating grid in an electric oven or a hair dryer. In the case of the bulb, it will cause it to glow.

In a separate light system where the low and high beam units are separate bulbs, each has only one filament and will illuminate when power is applied. Modern vehicles us one or more bulbs housed in a reflector assembly that appears to be one headlight unit. Keep in mind that there are also high intensity lights and LED lights as well used in these applications.

A concern that is often noted as well is when the headlight appears dimmer than the other, as if the dim light were about to blow out. So get your lights checked, replaced, and adjusted to see what's on the road ahead.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Everything works but brake light

Hi there. The complete circuit is powered from the stop lamp fuse in the instrument panel fuse block going to the brake light switch above brake pedal. When the brake is pressed, power comes out of the switch and then...

Q: 2007 Mustang Low-Beam headlight on only one side only comes on for 10 seconds then go outs, however high beams work fine!?!?

Hey there, thanks for writing in about your 2007 Mustang. The low beam circuit is monitored by the the Smart Junction Box. It's the fuse box in the right kick panel. Basically what this means is if the resistance, or...

Q: My car is experiencing intermittent low beam headlight malfunction

The headlights on this vehicle are controlled by a multiplex integrated control unit (MICU) located under the left side of the dash on fuse panel. The MICU contains all the headlight controls inside as an assembly and the low beam...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.