Four Reasons Why Subaru High Beams Function When the Headlights Fail

October 15th, 2023

Headlights are often an overlooked component in our vehicles, but their importance becomes glaringly evident when they fail at night. If you've ever found yourself driving in the dark and suddenly lost your headlights, it can be a disconcerting experience. In such a predicament, you might consider turning on your high beams, also known as "brights." In many cases, the high beams will still function, allowing you to safely navigate to the side of the road. Keep in mind that it's not advisable to drive with your high beams on in traffic, but it's a safer alternative to driving in complete darkness. Below, our certified Subaru service center in Salt Lake City explores the four primary reasons why your low beam headlights might fail while your high beams continue to work.

Among these four potential reasons, problems with the headlight switch are the least frequent but can still occur. In some models, the headlight switch is a protruding lever that can get caught on clothing or accessories like jacket sleeves or purse handles, leading to obvious issues with the switch. However, in most modern Subaru models, the headlight switch is located on the dashboard. While these switches can still experience malfunctions, they are generally considered reliable.

While not as frequent as the first two issues on this list, wiring problems occur more often than you might anticipate. With the shift to remote work in 2020, and many employees continuing to work from home, several vehicles spent extended periods parked in driveways and lots, providing ample opportunities for rodents seeking shelter. Regrettably, this can result in damage to your car's wiring system, impacting not only your headlights but various other components as well. Whether it's due to rodent interference or other forms of damage to your vehicle's wiring, headlight issues are just one of the potential problems you may encounter.

Modern vehicles, particularly Subaru models, are marvels of intricate engineering. Within your vehicle's electrical systems, including vital components like the headlights, fuses play a crucial role in safeguarding everything. These ingenious electrical components act as gatekeepers, permitting only a specific amperage to pass through. When the current exceeds this limit, the fuse will interrupt the connection, shielding the rest of the electrical circuit and associated components from harm. Occasionally, fuses may fail unexpectedly, and a straightforward replacement can resolve the issue. However, if the fuse blows again shortly afterward, it's advisable to consult a factory-trained expert for a more in-depth examination.

One of the common causes we frequently encounter for the malfunction of low beam headlights, while high beams continue to function, is a faulty headlight relay. In essence, relays serve as electrical switches, and both the low and high beams have their dedicated relays. Similar to fuses, relays can deteriorate over time. Given that low beams are used much more frequently than high beams, the relay responsible for low beams is more prone to failure. If you find yourself in a situation where the relay initially resolves the issue but subsequently fails again, it's indicative of a potentially more complex underlying electrical problem that warrants thorough examination.