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Subaru Headlights Are Like Christmas Tree Lights

I’m Saul Reisman here at Saul’s Automotive, and today we’re going to talk to you a little bit about the way the lights on your Subaru works as well as a little bit about the holiday season as well, since they actually both come together in the case of these vehicles.

If you drive a Subaru made between the years 2004-2012 or if you live in a state of Colorado and you have a family member, you probably have one of these vehicles in your family. You probably had a headlight bulb go out before and you did the basic replacement: unscrew a little cover behind the headlamp and put a bulb in it. No problem! This works in 99% of all cars, however, a lot of these more recent Subaru’s would have tremendous complaints of multiple bulbs failing at the same time or one bulb appearing brighter or dimmer than the other, accordingly. This is a little out of the ordinary and can sometimes be hard to diagnose if you’re not an automotive specialist or electrical specialist. This is a really basic problem and this comes down to something we remember as kids. You remember as a kid when you’re hanging Christmas lights, if one bulb goes out, it will shut out the entire string, and make all the bulbs go dim. You either had one string or half the string going out or a string where the light goes all the way until a certain point to where that opens and doesn’t make a pass.

Now that exact terminology is what we’re going to use for bulbs that we are going to talk about today. The way that Subaru wired the front end of their vehicles is quite unique. All their lighting is wired in series so when a bulb fails rather than being in a spot where that electricity continues on or independently for the other bulbs, it takes out the entire circuit and kills all of the headlamps. You ever had a time that you held a Christmas light string in your hand while it’s still on, and you see that one bad bulb. You pulled it out and it shocked you just a little bit? It’s because in the bottom of the Christmas light bulb there’s a shunt that sits open. When the bulb breaks that shunt closes while there’s still electricity passing through it, it lets the electricity to pass through to the next bulb. This is exactly what we’re going to show you with these Subaru bulbs. It might be a little hard to see them just because of how small they are, but we’re going to try and get the best details we can for you.

So the Subaru we had come into our shop had no headlamp bulbs whatsoever.

The high beams and low beams on the vehicle were completely inoperable. In this case, we started by checking the fuse circuitry and it was working fine. When we went to look at the bulbs themselves, the first low beam headlamp bulb had blown out its center section where the actual coil normally resides inside the bulb. This is the way most light bulbs typically fail, including the light bulbs that you would have in your household socket. The small little filament inside the piece of tungsten inside the bulb gets so hot that it eventually melts and breaks out. This is nothing out of the ordinary. What is out of the ordinary is that when this happens and the edge of the bulb burns because it heated up the glass housing on it and it sent that heat and that spark of electricity right back through the wiring on the other bulbs. Because these are wired in series, like a Christmas tree light—rather than being a blown fuse like in most cars, it immediately took the next bulb right next to it and blew its filament out too. It then sparked the same way and melted the back of it. Now both bulbs are generating electricity with nowhere to go and they both short back. When they shorted out, it sent the circuit to the high beams and the high beam bulbs physically exploded. Not only did they get so hot that they ruptured, but the actual filament inside of them is still intact; meaning, that they got so hot so quickly they didn’t even have time to heat up. The electricity hit them so fast from that surge they literally blew themselves to pieces.

Now in this case, not only do we replace the bulbs with the standard replacement so that we know that they are all going to work and we can get them back in running order, but we actually installed an update kit from Subaru that independently wires these headlamp bulbs so that this won’t happen again. We’ve seen major failures with this where one bulb fails and the others are operating well. That bulb’s out and electricity is still shorting and sparking and creates other damage in the vehicle. We’ve seen the electrical junction box under the hood, catch on fire and melt eternally. We’ve seen cases like this where all the bulbs get blown out and blown through.

So if you’ve got a Subaru and you got a bulb out, please give us a call at 303919.7769.

We replace all those bulbs completely free of charge as a courtesy service here at Saul’s Automotive. We want to make sure you’re safe. We want to make sure that you’re lit up. We want to make sure that other drivers can see you on the road. So if you have a concern about the bulb in your Subaru, you’ve got one that’s out, one that’s bright, one that’s dim or there’s something not quite working right. Please give us a call here at Sauls 303-919-7769. And remember: It’s just a Christmas light bulb.

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About the Author

Picture of Saul Reisman

Saul Reisman

Saul Reisman has been helping the residents of the Centennial State with their automotive needs for over ten years now. He finished his Associate Degree in Physics at the Community College of Denver. Saul is an active member of the Specialty Equipment Market Association and a board member of the Young Executives Network. He undergoes constant educational training through GMC, MOPAR, Ford, Snap-On, Borg-Warner, and Ozark Automotive, with an emphasis on diagnosis, repair, and improvement.

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