What Is a Tail Light? Tail Light vs Brake Light Explained
Short answer: a tail light (also called a tail lamp, rear light or rear position lamp) is the red light at the back of a car that comes on whenever your lights are on, so drivers behind you can see your car and how wide it is in the dark. It isn’t the same as a brake light. A brake light is much brighter and only shines when you press the brake pedal.
The two are easy to mix up, especially because they often sit in the same light unit. Here’s how each one works, and how to tell them apart.
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What does a tail light do?
A tail light does one simple job: it makes your car visible from behind. It glows at a steady, low level, so it shows other drivers where your car is and roughly how wide it is, in the dark, in rain and in fog.
It doesn’t tell anyone what you’re doing. That’s the job of the brake lights, indicators and reversing lights.
Tail light vs brake light: what’s the difference?
| Tail light | Brake light | |
|---|---|---|
| When it comes on | Whenever your lights are on | When you press the brake pedal |
| Brightness | Lower, steady glow | Much brighter |
| Colour | Red | Red |
| What it tells other drivers | “There’s a car here” | “This car is slowing down” |
On many cars the tail light and brake light come from the same unit. Some use a two-filament bulb, with a dim filament for the tail light and a brighter one for braking. On some LED units the same LEDs do both jobs at different brightness. That’s why a fault can look like a tail light problem when it’s really a bulb, a bulb holder or a wiring issue. Our guide on tail light not working explains how to find the cause.
The other lights at the back of your car
| Light | Colour | What it does |
|---|---|---|
| Tail light | Red | Shows your car’s position when your lights are on |
| Brake light | Red | Shines brightly when you brake |
| Indicator | Amber | Shows which way you’re turning |
| Reversing light | White | Lights up behind you when you’re in reverse |
| Rear fog light | Red | A very bright light for very poor visibility |
| Number plate light | White | Lights up your registration plate |
What’s inside a rear light unit?
A rear light unit usually contains a few parts:
- The lens: the red (and clear or amber) plastic cover you see from outside
- Bulbs or LEDs: the light source
- Bulb holders: the sockets that hold each bulb and connect it to the wiring
- The reflector: the shaped surface behind the light that directs it backwards
- The connector and wiring: the plug that links the unit to the car
Many cars have two lights on each side: an outer unit fixed to the body and an inner one on the boot lid or tailgate. Both can hold tail lights, so it’s worth checking which one you need.
Bulb or LED tail lights?
Older and simpler cars usually have bulb-type tail lights. You can replace a blown bulb without touching the rest of the unit. Newer cars often have LED tail lights, which give a sharp light that switches on quickly. On many LED units the LEDs can’t be replaced individually, so a fault can mean replacing the whole unit. You can browse both types in our used tail lights listings.
Why tail lights matter for the NCT
Working rear lights matter in Ireland. The NCT looks at your rear lighting, and brake lights have to be brighter than the tail lights beside them. We go through what the test checks in our guide to tail light and brake light NCT rules in Ireland.
Tail light FAQs
Is a tail light the same as a rear light?
Usually, yes. “Tail light”, “tail lamp”, “rear light” and “rear lamp” are commonly used for the same thing. “Rear light” can also mean the whole light unit, including the brake light and indicator.
Are tail lights and brake lights the same bulb?
Sometimes. Some cars use one two-filament bulb for both, and some LED units use the same LEDs at different brightness. Others use separate bulbs.
What colour should a tail light be?
Red. Brake lights must also be red, and the NCT checks the colour of brake lights.
Where can I buy a used tail light in Ireland?
You can browse used tail lights from breakers, garages and suppliers on Autolight, and filter by make, model, year, side and county.
Need a tail light?
Browse used car tail lights in Ireland and filter by make, model, year, side and county to find the exact fit.
