Don’t worry too much if your tail lights aren’t working, but the brake lights are. The problem should be easy to narrow down, although you might need professional help to fix it.
In the meantime, take extra care when driving, especially in conditions with reduced visibility. That isn’t just nighttime – be careful in tunnels, fog or mist, heavy rain, or any other inclement weather.
Remember, your tail lights aren’t for you. You don’t need to illuminate the space behind you. Rather, they’re for other drivers to know where you are.
Take extra care and avoid driving until conditions improve. A cop will pull you over and give you a ticket if you try to travel without tail lights. It’s illegal in every state and across most of the world.
In this guide, we will take you through several potential causes for this issue. We will list them in approximate order of likelihood (most probable first).
Let’s get into it.
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How Do You Test Your Tail Lights?
Testing your tail lights (and all your lights) is best with a friend or family member.
- Park up in a safe location (such as your driveway).
- Leave the ignition on and put the transmission in Park.
- Leave all the lights switched off for now.
- Get out of your vehicle and have your friend sit in the driver’s seat.
- Stand behind the car.
- Shout instructions to your friend in the car. For example, “Turn on the tail lights,” or “Press the brake pedal.”
- When they reply, check that the lights are illuminating. If any aren’t, take note.
If you don’t have anyone to give you a hand, it’s possible to do a vague check to see if your tail lights and brake lights work.
- Reverse up to a somewhat reflective surface, such as a window or painted garage door.
- Leave the ignition on and put the transmission in Park.
- Turn your lights on and look behind you to see if the surface lights up. In the reflection on a clean window, you might even see which lights work and which don’t.
- Press the brake pedal to check that those work.
While conducting these tests, you could also check the hazard warning lights and rear fog lights.
Reasons For Tail Lights Not Working But Brake Lights Coming On
Here are the most likely reasons for broken tail lights but working brake lights.
Blown Fuse
On the surface, a blown fuse seems like the most likely cause.
The fuse could have blown for the tail lights. This would stop them from working.
In your owner’s manual, you’ll find the fuse box diagram. This tells you which circuit each fuse monitors and the current at which it blows.
Note that the fuse box layout depends entirely on the manufacturer’s design. Some might fit one fuse to both tail lights. Others would separate the circuits, putting one fuse on each. You might find that the fog light fuse is included with both, with one, or separately.
Checking for a blown fuse is simple. Park in a safe location and turn the engine off. Use the needle nose pliers to extract the relevant fuses and check them for breaks. Use a test light or multimeter to look for continuity.
If any fuses have blown, you’ll need a new one. Ensure you use the correct amperage, as detailed in the diagram. You’ll find fuses at any good parts store.
Turn the car and headlights back on to see if the tail lights work.
Two Blown Tail Light Bulbs
The probability of both of your bulbs wearing out at the same time is very low. Not impossible! But extremely improbable.
It’s more likely that one tail light went out some time ago, and you didn’t realize it. After all, how often do you check your tail lights?
The other one might then blow, leaving you with no tail lights but working brake lights.
It’s a basic fix, although bulbs can often be fiddly.
Other potential bulb-related issues include simply using the wrong type.
Remove the old bulbs and check to see if the filaments have blown. Replace them with new parts from any good hardware store or parts website.
Ask for help from a mechanic or store technician if you need it. It won’t cost much at all.
Not Using Dual-Filament Bulbs When You Should
Many cars use a dual-filament system at the rear. One bulb lights up a separate filament for the brake light and tail light.
If you’ve fitted single-filament bulbs to a double-filament circuit, only the brake lights or the tail lights will illuminate. The other won’t.
These could be causing your problem if you’ve only just changed the bulbs – or just noticed.
Replace your bulbs with the correct type (found in your owner’s manual). You should also check for damage to the plugs and look for any blown fuses.
Don’t be afraid to ask for help from a local mechanic to change bulbs. It’s often cheaper than buying one from a hardware store because of the shop’s trade discount.
Wiring/Plug/Ground Issues
Water intrusion or poor electrical design could lead to deeper electrical problems. These could include corroded connections (including grounds) or plugs.
You’re more likely to see this on older vehicles.
They’re often caused by water intrusion. For example, corroded plugs could be caused by not fitting the tail light housings properly.
Deeper electrical problems are difficult to pin down, especially if they’re somewhere between the battery and the bulbs.
You’ll need an automotive electrician if any of these turn out to be your issue.
Unless the tail lights are all on the same circuit, these likely aren’t the root cause of your tail light not working.
Having two fixtures rust out at precisely the same time would be unusual.
Faulty Headlight/Tail Light Switch
You turn the switch to activate your low-beam headlights and tail lights. These are always on the same circuit.
The switch is usually a dial. You’ll find it on the dashboard next to the steering wheel or sometimes on one of the stalks.
These switches can break. However, you’ll almost certainly lose the headlights at the front too.
Thus, the switch might be at fault if your headlights also aren’t turning on.
You’ll need help from an expert mechanic or auto electrician to replace this component.
Failing Ambient Daylight Sensor
Do you leave your car’s headlight and tail light settings on AUTO?
If it’s getting dark and the headlights aren’t coming on, the ambient daylight sensor might need to be fixed. If you turn the switch to activate the headlights and they come, it’s definitely broken.
The tail lights also won’t be coming on.
The ambient daylight sensor can be found behind the rearview mirror. You’ll need a professional to swap the part out for you.
Did You Turn Your Lights On?
It’s best to be thorough. Are the lights even turned on?
If you find this is the root cause, it’s best to not tell anyone and quickly move along with your day!
In all fairness, it could happen to anyone.
Why Do I Have Brake Lights But No Tail Lights?
Although this guide has taken you through almost all the possibilities, the most likely causes lie with the bulbs or fuses.
In almost every case, replacing these with new ones will solve your problem. Get a mechanic to change them if you’re unsure what you’re doing.
Sometimes, there’s a more serious fault. You’ll definitely need assistance from an automotive electrician in these situations.
Avoid driving in poor visibility (including at night) without tail lights, even if your brake lights work. As always, stay safe!
