Brake Lights Out on Left Side

Hey guys, I’m trying to get my brake lights working and am unsure of what the next step might be.

There’s 2 lights on both sides, and both the left ones are out. They do power on as parking lights and when turning the alarm on and off.

I’ve tried swapping the bulbs and cleaning the sockets. One of the other parts I was thinking didn’t make sense since the issue is on one side. When I swapped the bulb it looked like part of it was melted. Thanks!

Check the ground wire to the socket case. Should be zero ohms.

Turn the lights on and check for voltage to the buttons the bottom of the bulb touches.

Year? On my 2008 and 2009 those are dual filament bulbs, so one function can work but not the other. Have you tried swapping bulbs from the right side to the left side to see if that makes any difference?

I outright replaced both bulbs.

I’ll try checking that as soon as I can!

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You’ve checked the fuse, of course. The deformed terminal looks odd, I haven’t encountered this and presume it results from overheating, possibly due to poor electrical contact at the socket. How does the corresponding contact on the socket appear?

More of a stretch, but if the brake light circuit became stuck on, that filament and its connections would run hotter than usual. A short circuit within the bulb also would result in overheating, but I don’t see how that would occur and it more likely would blow a fuse. Get your meter out.

If you go much further it might be useful to consult the wiring diagram.

An easy way to test if all the bulbs are working is to hit the 4 way flashers. Try to isolate the wire going to the brake filament and trace it back to the connectors. Might had pulled a wire loose or something.

The contact points seemed ok to me but I’m also new to this. The fuses were ok, I checked them after I swapped the bulbs.

I’ll have to use a meter next I’ve just never used it before!

Turn on the headlights, the taillights should come on. Then have someone step on the brakes, if the left taillight goes out, then you have a bad ground. Look for a black wire coming from socket and follow it to where it is screwed to a metal part of the vehicle.

There would be no separate fuse for one side, so if one works the fuses are good. Do you have a turn signal working on that side? Agree with the ground as a likely. A length of wire with alligator clips can help. Ground to bulb, connector to bulb, etc. Then isolate from there. I’d be looking for smashed or melted wires, loose connector, wire pulled out etc. Any recent cargo loads that might have disturbed something?

Just a story to help expand the possibilities. I’ve had two cases of melted wires that stumped the mechanics. On our 61 Merc I had it out and when I used the signal light all four lights flashed. This was before 4 way flashers. Mechanic pull the steering wheel etc. and couldn’t find it and sent me home. Then I started looking around and remembered the night before I had hit something in the road and the exhaust got louder. Crawling under the car I discovered a hole in the resonator that had melted the wires above. A little repair work and all was well.

On my 67 Buick wagon, I got stopped for tail lights being out. Changed the fuse but kept on blowing. Crawled under it and discovered the wires had fallen down on top of the exhaust pipe. As soon as it was driven long enough the wires would melt and short out, then back to normal when it cooled off. Just sayin’ to think outside the box a little to before the problem started.

Now, how would you know that?

The OP didn’t provide the year of the vehicle.

So, it’s impossible to look up the wiring diagram to see if that’s not the case.


Is the bulb in the pic an old one? I’m assuming it is; sans my eyeglasses. You might try snagging the contacts inside the bulb socket and try bending them up a tiny bit. Ideally, testing the contacts with a test light or voltmeter would be preferred.

At times Subaru has had some problems with the contact domes on the bulbs is why I asked. They do look noticeably distorted and that issue has been around a quite a while.
Vibration over time will cause the domes to take on a concave shape from rubbing against the socket tangs and that prevents a good contact against the tangs in the socket.

If unfamiliar with meters take care not to apply voltage to the meter when either the current (and maybe the resistance) modes are selected, either by the dial or the meters sockets. It’s an easy mistake to make, especially if one previously measured current. If lucky this just blows a meter fuse but it often either wrecks the meter outright or ruins it’s calibration.

The brake lights are tied into the emergency flasher and turn signal circuits. Do the turn signals work on that side, or do the flashers work on that side? If one of those systems works then the trouble isn’t with the lights.

Yeah, posts 6 and 9, but @Tester suggested there might be a fuse for the left side. We’ll probably never know the answer though.

The turn signals on this vehicle are amber, separate from the brake lights.

The lights stay on – just no brake!

Thank you for the tip!! I’m gonna have to look up how to use it haha

So I’ve checked the fuses before and they’re good. There’s not separate for each side. The turn signals work as well.

I thought I’d included the year which is my fault – it’s a 2002.

I think it’s the socket after looking it over. Issue is it’s not carried most places.

Thank you everyone for helping me!

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